A 17-year-old boy has been arrested in last week’s shooting at a Spirit Halloween store in California that killed a pregnant woman and injured six other people, police said Monday.

The suspect, whose name will not be released because he is a minor, will be charged with one count of murder but could face an additional murder count because 31-year-old victim Constance Hages was pregnant, Fairfield Police Chief Dan Marshall said.

The teen was arrested in Suisun City, a municipality adjacent to Fairfield, where the shooting took place at Solano Town Center mall around 8:30 p.m. Friday, police said at a news conference Monday.

A 16-year-old boy and two men, ages 19 and 32, were left in critical condition, Marshall said. A 23-year-old man was stable in critical condition at a hospital, and two other men, ages 19 and 43, were treated for gunshot wounds and later released, according to authorities.

All but one of the victims still hospitalized Monday had been stabilized, with one still in critical condition, Marshall said.

The shooter entered the store and targeted someone specific inside when he opened fire, said Officer Michelle Belyea, a police spokesperson. Marshall said that the shooter used a handgun and that there may have been a previous altercation between him and a victim.

The suspect opened fire on a vehicle at a local high school last year and was in custody for a few months as a result, Marshall said. He bemoaned what he characterized as a lack of accountability in that case.

“This event shouldn’t have even occurred,” Marshall said. “California has gotten extremely soft on accountability with youth.”

He said detectives identified a suspect hours after the attack but didn’t want to tip him off. The teen was arrested at his home Monday afternoon, Marshall said.

The suspect is believed to have acted alone, he said.

Fairfield, a city of more than 122,000, is about 45 miles northeast of San Francisco.