A celebration turned into a nightmare for one couple on the dance floor.

Jeff and Nancy Liu arrived at the dance studio in Monterey Park on Saturday night to celebrate the Lunar New Year. But what should have been a night of celebration turned into a night of horrors, their daughter, Juno Blees, would later recount, when Mr. Liu saw a man storm in with a gun and open fire.During the chaos, Mr. Liu saw his wife collapse, Ms. Blees said, and has not seen her since.

The family is praying that she was taken to a hospital and that they will be reunited soon. The couple, who emigrated from China more than 25 years ago, rarely left each other’s side, Ms. Blees said in a phone interview on Sunday.

Two bullets grazed Mr. Liu, his daughter said, causing minor injuries to his shoulder and his back that sent him to a hospital. “He bled a lot, but the doctors said it was non-life threatening,” Ms. Blees said.

Mr. Liu, 62, was discharged Sunday and returned home to recover, Ms. Blees said. She hoped that the reason her mother, who is 63, has not been located is because she forgot to bring her identification card to the dance hall. Ms. Blees said she visited the victim resource center set up by Monterey Park officials on Sunday afternoon and was told to leave her contact information in case her mother is found.

“We are mentally preparing for the worst,” she said.

Mr. Liu told his daughter that he and his wife frequented Star Ballroom Dance Studio, where the clientele is mostly middle-aged or older residents for the area, many of them migrants from China like her parents. “They know everyone,” Ms. Blees said.

Mr. Liu was standing toward the entrance, watching people dance, when the gunman began shooting. He told his daughter that he saw the gunman open fire at a dance hall operator who was selling tickets at a booth. Ms. Blees said her father “got on the floor right away.”

“He felt heat on his shoulder,” she said. “That’s when he knew that he probably got hurt.”

Panic and screaming followed. “Then he said he saw the gunman take off after opening fire,” she said. During the commotion, Mr. Liu saw his wife fall to the floor and lost sight of her as he was taken into an ambulance.

“He saw her collapse, and they got separated,” she said. “They got separated during the panic that ensued. So we are hoping for the best right now.”

Susan C. Beachy contributed research.