English class had let out and Oswaldo Fajardo, 39, was standing in a parking lot talking to a female classmate when a man ran up and stabbed him, reported Santa Rosa police on Wednesday.
The attacker was the woman's husband, said Santa Rosa police Sgt. David Linscomb.
Fajardo of Santa Rosa remained hospitalized Wednesday with a severe stomach wound.
Officers late Tuesday night arrested Miguel Ascencio, 35, of Santa Rosa, suspecting he was trying to kill Fajardo.
The motive remained under investigation. The couple reportedly had been having relationship issues, Linscomb said.
"There doesn't appear to be any previous issues between the husband and the victim. It seems like they didn't even know each other," said Linscomb.
Fajardo and the woman were classmates in the Tuesday night English class at the Santa Rosa Junior College satellite center on South Wright Road.
Class had let out and as the two walked to their cars they stopped to talk.
"(Ascencio) appeared out of nowhere," Linscomb said.
Driving his car, the man sped up to the two, got out, stabbed the man and ran from the parking lot, said Linscomb.
The 33-year-old Santa Rosa woman and Fajardo got into her car and left.
As she drove him to a Stony Point Road shopping center, Fajardo called 911 at 9:48 p.m. to report he'd been stabbed.
At the center they met police and paramedics. He was taken to Santa Rosa Memorial Hospital for emergency surgery.
Back at the center officers found no sign of the suspect. They found Fajardo's 2000 BMW in the parking lot with four punctured tires, said Linscomb.
Officers arrested Ascencio at his Coffey Lane home on suspicion of attempted homicide.
He remained in the Sonoma County Jail Wednesday without bail due to an immigration hold.