A package that officials said contained two vials of a "homemade explosive substance" was discovered near the Arizona State Capitol in downtown Phoenix on Monday.
Capitol Police said they temporarily locked down the headquarters of the Republican National Convention after a suspicious package with two vials of blood was found.
Federal authorities are investigating suspicious letters sent to election offices in five states.
A series of threatening letters containing a mysterious white powder is raising concerns that Republican lawmakers in Kansas are being targeted.
Since Friday, about 100 letters have been received by Kansas GOP lawmakers and Kansas Attorney General Kris Kobach, who is also a Republican, officials said.
The number more than triples the amount when the situation was first reported early Friday evening.