PASADENA >> A man allegedly robbed a woman at gunpoint in his apartment, then barricaded himself when police showed up Monday. He holed up for nearly seven hours, until his mother called and police convinced him to surrender.

“She called her son on the phone. The suspect answered,” Chief Phillip Sanchez said. The phone was passed to a member of the Crisis Negotiation Team, who convinced the man to surrender, the chief said.

Henry Sinclair Hsieh, 20, of Pasadena was arrested on suspicion of assault with a firearm, according to Pasadena Police Lt. Tracey Ibarra. She said officers also found a handgun in the apartment.

His girlfriend, 18-year-old Hyeeun Joyce Jung of Los Angeles, was arrested on suspicion of assault. Ibarra said Jung allegedly punched the victim during the robbery at 70 Harkness Ave.

• Photos: Suspect in custody after standoff in Pasadena

When Pasadena police got a 9-1-1 call just after 1 a.m., the police dispatcher could hear conversations on the open line but wasn’t sure what was happening, Ibarra said.

The dispatcher called the number and reached a woman, who said she had been robbed at gunpoint and locked in a room.

“The caller stated she fled the location and was calling police from her vehicle,” Ibarra said.

She said the woman was visiting the Harkness Avenue apartment earlier, when the suspect allegedly put a gun to her head and demanded her purse. There were other people in the room at the time.

The suspect got the purse but returned it prior to the victim leaving the apartment, Ibarra said.

Sanchez said that when officers showed up at the apartment just before 5 a.m., they were met by a man who retreated inside the residence. The man was seen carrying a firearm.

Officers closed off the area and evacuated residents, including the other people inside the suspect’s apartment.

• Video: Police use flash bang grenade at Pasadena barricade situation

The Pasadena police Special Enforcement team, which is the department SWAT, and the Crisis Negotiation Team were called in. They deployed Flash Bang devices, called the apartment and used a loud speaker but got no response from the barricaded man.

Police contacted the suspect’s mother. With her help, police were able to get him on the line. He surrendered without incident around 11:40 a.m.

Hsieh, who is on probation for a prior robbery arrest, is being held in Pasadena jail on $50,000 bail. Police said he could face a robbery charge,

Jung, who was arrested at the scene, was booked at Pasadena jail. She posted bail and was released.

Several of the evacuated residents waited at Harkness Avenue and Colorado Boulevard during the standoff. Among them was Santos Martinez, who was barefoot and wore shorts and a shirt.

“(Police) didn’t tell us what was going on. I was just curious,” Martinez said.

He doesn’t recall any prior incidents in his neighborhood in which police were called.

A resident, who declined to give her name, said she heard police banging on one unit around 5 a.m. and demanding the person come out.

Her 1-year-old son and 5-year-old daughter were asleep when police told the family to evacuate.

“We didn’t have time to pack a diaper bag or anything,” she said. She said she was glad the American Red Cross provided her with diapers.