A source told ESPN that Odom is fighting for his life and "the next 48 hours are critical."
Sheriff Sharon A. Wehrly said in a statement Tuesday that authorities were called at about 3:15 p.m. to Love Ranch in Crystal, Nevada, about 70 miles outside of Las Vegas, for a report of an unresponsive man needing an ambulance.
Odom, 35, was stabilized and taken to Desert View Hospital in nearby Pahrump, the statement said. Officials then tried to have him airlifted to Las Vegas, but the 6-foot-10 Odom was too tall for the helicopter that was available, so he was driven by ambulance to Sunrise Hospital and Medical Center.
Wehrly said Wednesday that investigators sought a warrant to obtain a blood sample to determine if Odom suffered a drug or alcohol overdose.
Lakers starKobe Bryant, who exited Tuesday's exhibition game -- also in Las Vegas -- in the third quarter for a lower leg contusion, visited the hospital, sources told ESPN's Ramona Shelburne. The Los Angeles Daily News reported that Lakers general manager Mitch Kupchak visited the hospital as well.
Dennis Hof, who owns Love Ranch and other legal brothels in Nevada, said his staff picked up Odom from a home in Las Vegas on Saturday.
"He just wanted to get away, have a good time and relax,'' Hof told The Associated Press in a phone interview.
Hof said Odom was "happy, he was sleeping every night" while visiting, but two women went to check on Odom on Tuesday afternoon, after not hearing from him since early morning, and they found him face down and unconscious.When they turned him on his side at the direction of a 911 operator, Odom started "throwing up all kinds of stuff."
Hof said Odom had been taking herbal Viagra and had drunk part of a bottle of cognac since arriving, but Hof had no knowledge of Odom's use of any other drugs.
"It's incredibly sad,'' said Hof, who turns 69 on Wednesday. Hof is known for his own onetime reality show, "Cathouse,'' on HBO.
Odom's hospitalization was first reported by TMZ.
Odom, who won two NBA championships with the Lakers in 2009 and 2010, last played in the NBA in 2013. He saw recent reality TV fame through his four-year marriage to Khloe Kardashian.
Kardashian, who filed for divorce in 2013 citing irreconcilable differences, has been by Odom's side at the hospital since Tuesday evening, a source close to the Kardashians told The Associated Press.
The two were married in 2009 in a large ceremony taped for the E! network, following a whirlwind engagement that also was filmed.Their divorce has not yet received final approval from a judge.
Former Heat teammateDwyane Wade was among several NBA players to offer their support on Twitter:
Lakers coach Byron Scott expressed his support of Odom to the media after the Lakers'107-100 exhibition loss to theSacramento Kings.
"Obviously, our hearts and our thoughts and our prayers are with Lamar and his family," Scott said. "It's obviously something that you don't want to hear before the game because I think the people that knew about it, we were all thinking about it.... I obviously feel for him and hope that he'll be OK."
Lakers guard Nick Young touched on how Odom's ties to the Lakers made Tuesday's news especially difficult on certain members of the organization.
"It's tough. It's tough because these guys were real close to him here, and the Laker family really loved him. For anybody to be down like that and go through so much, it's tough. Your heart goes out to him."
A distraughtMetta World Peace, a former teammate of Odom's, was lost for words upon hearing the news about his childhood friend.
"I don't even know what to say. There's not one word that I can say right now that's going to make sense. I don't know what to say right now."
Golden State Warriorsinterim coach Luke Walton, Odom's Lakers teammate for seven seasons, spoke to the media upon discovering Odom was hospitalized after the Warriors' Tuesday preseason game.
"Lamar is a brother to me. I love that man. My prayers are with him," Walton said.
Knicks coach Derek Fisher, a teammate of Odom's with the Lakers, weighed in as well.
"Lamar Odom is one of the greatest people I've ever known. That's the way I see him," Fisher said. "I don't view him through the prism of choices that he's made, I view him through the heart and soul of the person that he really is. I'm obviously hoping that he can pull through this and that in some fortunate way this becomes the beginning of a different ending."
Odom spent the best years of his career with the Lakers. He won two championship rings, as well as the NBA's sixth man of the year award in 2011.
After seven years in purple and gold, he was crushed in December 2011 when the Lakers attempted to trade him to New Orleans in a multiplayer trade for Chris Paul. Odom eventually went to Dallas in another deal but was out of the NBA just two years later.
Some troubles that Odom met before and during his NBA career appeared to worsen after he left the league. That includes a no-contest plea to drunken driving shortly before his divorce.
Odom most recently played for the Los Angeles Clippers during the 2012-13 season, his second stint with the team. He averaged 4.0 points, 5.9 rebounds and 1.7 assists while playing all 82 games. He became a free agent in July 2013, but no NBA team signed him.
Clippers star Chris Paul said in a statement: "I wanted to extend love and support to one of our NBA brothers, Lamar Odom. We love you, man. Keep fighting. He's a member of this fraternity, our basketball brotherhood, and we love you and we're all there for you, man."
In February 2014, Odom signed with a Spanish team on a two-month deal, but a month later, he returned to the U.S. because of a back injury. That April, he signed with the New York Knicks for what remained of the season, but he didn't appear in their final game and was waived that July.
Odom was suspended during the 2000-01 season for violating the NBA's anti-drug policy for the second time in eight months. During the 2010-11 season, a cousin he was close to died, and Odom was a passenger in a vehicle involved in an accident that killed a cyclist in New York.
Odom played one season atRhode Islandbefore being drafted No. 4 by the Clippersin the first round of the 1999 NBA draft. He was named to the All-Rookie team and playedfour seasons with the team before becoming a restricted free agent and signing with Miami.
He helped the U.S. win a bronze medal in the 2004 Athens Olympics.
Born Lamar Joseph Odom on Nov. 6, 1979, in New York City, he was raised by his grandmother after his mother died of cancer when he was 12. His father was a drug addict.
In 2006, Odom's 6-month-old son, Jayden, died from SIDS while sleeping in his crib in New York. He has a daughter, Destiny, and a son, Lamar Jr., from a previous relationship.
Information from ESPN.com's Baxter Holmes, Ian Begley and Arash Markazi and The Associated Press was used in this report.
Shelburne: Tragedies of Odom's life shared by those who love him
Ramona Shelburne looks at the profound impact Lamar Odom had on his teammates and the people around, and how the tragedies in Odom's life have shook his soul.
Odom unresponsive, hospitalized
ABC News correspondent Kayna Whitworth reacts to the news that former NBA star Lamar Odom was hospitalized Tuesday after he was found unconscious at a Nevada brothel.
Lamar Odom found unresponsive, taken to hospital
Former Lakers star Lamar Odom was found unconscious Tuesday at Love Ranch, a Nevada brothel, and was rushed to a Las Vegas hospital.