The brother of the suspect charged with 10 counts of murder in Monday’s shooting at a Colorado supermarket has spoken out about his sibling in a new interview.

Shortly after Boulder Police identified the suspect as 21-year-old Ahmad Al Aliwi Alissa on Tuesday, The Daily Beast published a conversation with his brother, Ali Aliwi Alissa, who described his sibling as “very anti-social.”

“When he was having lunch with my sister in a restaurant, he said, ‘People are in the parking lot, they are looking for me.’ She went out, and there was no one,” the 34-year-old Ali told The Daily Beast. “We didn’t know what was going on in his head.”

Ten people, including a police officer, were killed in the shooting at the King Soopers grocery store, which police responded to at about 2:40 p.m. local time Monday.

Police said at a news conference Tuesday that gunfire was exchanged after officers arrived, and that the shooter sustained a leg injury. He was taken into custody shortly before 3:30 p.m.

The suspect was identified as Ahmad Al Aliwi Alissa during the news conference. He has been charged with 10 counts of murder in the first degree, police said.

A motive for the shooting has not been determined.

On Tuesday, police also named the 10 victims, who ranged in age from 20 to 65.