WEST VALINDA — Two men were behind bars Tuesday, and investigators sought two more, on suspicion of a violent robbery at a home in which medical marijuana was being legally grown, authorities said.

Srun “Sean” Ly, 38, of Fontana, and Chanthoern Chhuon, 31, of Stockton, are accused of home-invasion robbery, assault with a deadly weapon and making criminal threats in connection with the Jan. 4 crime in the 1300 block of Edanruth Avenue, Sgt. Steve Kim of the Los Angeles County Sheriff’s Asian Gang Team said.

“All four suspects forced their way in,” the sergeant said. “They started beating up the victim. At one point, one of the suspects pistol-whipped the victim in the head.”

The robbers then bound the hands and feet of the victim with tape before fleeing with about $2,000 in cash and several pounds of marijuana, Kim said.

The victim, a man in his 20s, was knocked unconscious in the 1:30 p.m. attack, he said. After waking up early the next morning, he was able to free himself and call for help.

The victim recognized two of the robbers and knew them by a first name and a nickname, Kim said. Both had assisted the victim in the marijuana growing operation, which was being done in compliance with state law in partnership with a medical marijuana dispensary.

Investigators identified Ly — alleged member of the Wah Ching street gang in Los Angeles — as a suspect and arrested him without a struggle in the early morning hours of Jan. 6, according to sheriff’s officials and booking records.

Kim said Chhuon — an alleged member of the Original Bloods street gang in Stockton — was also arrested without incident at his Stockton home on Jan. 13 by a local police SWAT team.

The two robbers who remained at large Tuesday were described only as a Latino man and a man of unknown race.

According to sheriff’s booking records, Chhuon was being held without bail, while Ly was being held in lieu of $1.23 million bail.

Both suspects were due for arraignment Wednesday in El Monte Superior Court.