"We know he's dangerous; he's displayed that," Fremont Police Detective Bill Veteran said.
Alexander Diaz, 36, is from Southern California. He is a parolee, convicted of grand theft.
Police say he used his stolen van as a weapon Monday morning. Diaz allegedly aimed it straight at Officer Patrick Brower as he stopped his motorcycle in the center of the road.
"This wasn't a traffic accident, this was Mr. Diaz trying to get away by running over our police officer," Veteran said.
Police say the van dragged Brower and his motorcycle through two lanes of traffic. The van came to a sudden stop at Warm Springs Boulevard near I-880 when the vehicle hit a light pole.
The collision pinned Brower between the van and the street light. It took rescue workers 15 minutes to free Brower from the mangled wreckage.
Dozens of heavily armed officers went looking for the driver, some with dogs. They set up roadblocks, searched cars and trucks.
Early Monday night, they got a break. Police stopped a BART train at the South Hayward station and detained someone they call an "associate" of Diaz's; a man who investigators say then helped identify Diaz as the driver.
Fremont police are now in touch with authorities in Southern California.
"We are working closely with them to try and locate people who might know him, family acquaintances, that sort of thing," Veteran said.
Brower, 43, is listed in stable condition at a San Jose hospital after going through surgery.
"He had extensive damage to his leg, compound fractures, crushed toes, that kind of thing and they put some rods in there," Veteran said.
A no-bail warrant has been issued for Diaz for the attempted murder of a police officer.