Around 11:20 a.m., deputies responded to a burglary in progress in the 14000 block of Chrisland Avenue in unincorporated San Jose, sheriff's Capt. Rick Sung said.
Two women were inside the home at the time of the intrusion, and they told deputies that five men had entered the residence and that at least one had a gun, according to Sung.
Responding deputies saw the suspects trying to flee and were able to apprehend four of them, Sung said. The fifth evaded authorities, and they are still searching for him.
A sheriff's helicopter was deployed for the search, as were K-9 units from the San Jose Police Department, Sung said.
Some schools were placed on lockdown, as were the Dr. Roberto Cruz-Alum Rock and Educational Park branch libraries.
A librarian at the first library, located at 3090 Alum Rock Ave., said staff there were told by the sheriff's office to shelter in place around 1:20 p.m.
Staff at the Educational Park branch at 1772 Educational Park Drive said they had also been advised to shelter in place.
East Side Union High School District Superintendent Chris Funk said no schools in his district had been affected, but that he had been briefed on the situation and was told several other schools were locked down.