A man and a woman were seriously wounded after assailants barged into their Concord home and shot them both in what may have been a botched drug robbery, police said.

Just before 10 p.m. Wednesday, officers responded to reports of gunfire at the home in the 2900 block of Bella Drive and found a 28-year-old man and a 29-year-old woman wounded, said Cpl. Chris Blakely, a spokesman for the Concord Police Department.

The victims were taken to a hospital, where they were in stable condition.

Officers discovered “pounds” of marijuana on the second floor of the victims’ home, Blakely said, leading police to suspect the shootings were motivated by an attempted theft of the drugs.

The woman was shot in the right arm, and another bullet grazed her chest, police said. The male was injured more severely, taking multiple bullets to the upper body and one to the head.

It’s unclear whether either resident has a medical marijuana permit, police said.

Police believe the two assailants wore black clothing and made their getaway in a dark-colored vehicle. Neighbors called police after hearing seven to 12 gunshots at the house.

Officers recently held a community meeting in the normally quiet neighborhood and residents who attended commented on “how peaceful it is,” Blakely said.

“For that area, it’s definitely unusual to have something like this,” he said.

Anyone with information on the shooting is asked to call the Concord Police Department at (925) 671-3030.

Michael Bodley is a San Francisco Chronicle staff writer. Email: mbodley@sfchronicle.com. Twitter: @michael_bodley