Ten people are dead and a suspect has been arrested following a mass shooting at a grocery store in Boulder, Colorado last night (March 22). The tragedy arrives as the second mass shooting in less than a week, following shootings at three Atlanta-area massage parlors that left eight people dead last Tuesday (March 16).

“This is a tragedy and a nightmare for Boulder County,” Boulder County District Attorney Michael Dougherty said at a press conference last night. “These were people going about their day, doing their shopping. I promise the victims and the people of the state of Colorado that we will secure justice.”

One suspect is currently in police custody and receiving hospital care for wounds, USA Today reports. Police have not said whether or not they believe the suspect acted alone in the attack. As of Tuesday morning (March 23), authorities have not released the suspect’s identity, but a video published by Reuters showed a handcuffed man with a bloodied leg being taken away from the scene in an ambulance. According to police, the suspect was the only person with non-threatening injuries; all 10 victims were killed.

Police only revealed the identity of one victim, 51-year-old police officer Eric Talley, who was one of the first to respond to the shooting. D.A. Dougherty promised a “painstaking investigation” and said Talley’s “life was cut much too short” during the conference.

The names of the nine other victims will be released after they are identified and their families are notified, which Boulder Police Chief Maris Harold said the department is working “around the clock” to accomplish.

“Our hearts go out to all families impacted,” Harold said, adding that Talley’s actions were “heroic.”

Police have not yet identified a motive in the shooting nor said whether the shooter knew his victims. Witnesses said on Monday that gunfire began in the parking lot of a King Soopers grocery store and then moved inside the building. Police have not disclosed what weapon the assailant used, but said they were alerted “about a possible person with a patrol rifle.”

After the suspect was arrested, the shelter-in-place directives in the area were lifted.