
SAN DIEGO -- Two teenagers are being investigated by authorities as the suspected gunmen who opened fire at the Islamic Center of San Diego, killing three men before killing themselves, a number of sources tell ABC News.
Authorities believe Cain Clark and Caleb Vazquez are the shooters in Monday morning's attack, which is being investigated as a hate crime.
Both suspects, ages 17 and 18, died from apparent self-inflicted gunshot wounds, police said. They were found dead in a vehicle stopped in the middle of a road near the center, said San Diego Police Chief Scott Wahl.

Three men were killed in the shooting.
Among those killed was a mosque security guard, who police believe "played a pivotal role" in keeping the attack from being "much worse," Wahl said. Families at the Islamic Center who knew the security guard said he was a father of eight.
The Islamic Center of San Diego identified the security guard as Amin Abdullah.
"This guy, like, it didn't matter who walked up, who came, any random person could just walk up. He would greet them, make sure they're OK," said a man who considered the security guard a friend.
The other two victims have not been identified.
Heavily armed FBI agents were seen entering one of the suspect's home Monday night. They had guns drawn when they approached the door.
Two hours before the initial shooting call came in, police said they received another call from a parent reporting a runaway juvenile. The teen's parent told police that several weapons from her home were missing, a vehicle was missing, and her son may have been suicidal. She said he was with another person, and they were dressed in camouflage.
That information triggered a police response, and police began using tools like license plate readers to track the vehicle around San Diego. Officers were sent to a mall in Fashion Valley and Madison High School, trying to zero in on the suspects.
Sources tell ABC News that anti-Islamic writings were found in the vehicle with the two teens. Search warrants are being executed at homes affiliated with the two suspects.

Meanwhile, police departments in major cities across the country are monitoring the situation. In Southern California, the Los Angeles Police Department said there's currently no known threat to L.A., but the department remains vigilant: "Out of an abundance of caution, we are providing extra patrols at mosques, Islamic centers, and all houses of worship across the City to ensure our communities are safe and feel supported."
In New York City, the NYPD said there's "no known nexus to NYC or specific threats to NYC houses of worship," but the department said it is increasing officer deployments to mosques "out of an abundance of caution."
The Chicago Police Department said in a statement that "while there is no actionable intelligence in Chicago, we are paying special attention to places of worship throughout the city out of an abundance of caution."
The Islamic Center's website says its mission is to not only serve the Muslim population but also "work with the larger community to serve the less fortunate, to educate, and to better our nation." Five daily prayers are held there, and the mosque works with other organizations and people of all faiths on social causes.
ABC News contributed to this report.