Ten people were killed in a shooting spree at a grocery store in Boulder, Colorado, including one police officer, local law enforcement confirmed. A suspected gunman has been arrested.

"Our hearts go out to all families impacted. There are ten fatalities," Boulder Police Chief Maris Herold told a press conference on Monday evening, several hours after a gunman went on a shooting rampage at a King Soopers supermarket in the Table Mesa neighborhood.

Among the victims was officer Eric Talley, who was first to respond to the reports of a gunman with "a patrol rifle" at the store, Herold said, calling the officer's conduct "heroic."

Boulder County District Attorney Michael Dougherty also praised the officer. "My heart goes out to Eric Talley's family," he said while extending condolences to the families of those killed.

Other victims' names have not been released as police still have to notify their next of kin.

One suspect has been taken into custody and is undergoing treatment for an injury. While police declined to identify the suspect, a live feed from a local news outlet earlier showed one man being led away from the shooting scene in handcuffs. He was partially naked and visibly bloodied. Police said that the only person who suffered injuries in the incident was the suspect.

No motive for the shooting has been established yet, with police saying the investigation is in its early stages.

Along with police, federal, state, and local agencies are taking part in the probe.

An earlier report of an "armed, dangerous individual" at a location near the grocery store, which prompted a shelter-in-place notice, turned out to be unrelated to the store shooting, police said. 

Update:

Police identify suspect in Boulder store shooting as Ahmad Alissa, say they've found no motive.

In Boulder, Colorado, police have identified 21-year-old Ahmad Alissa as the suspected gunman who killed ten people in a grocery store shooting spree. Alissa's motive is still a mystery.

Ten people, including a police officer, were killed on Monday when a gunman opened fire at the King Soopers supermarket. Officers arrived within minutes and shot the suspect, who was seen on video being taken into custody.

He was identified on Tuesday as Ahmad Al Aliwi Alissa. In a press conference on Tuesday morning, Boulder Police Chief Maris Herold said that Alissa was a resident of Arvada, Colorado, and has "lived most of his life in the United States." He is currently in hospital receiving treatment for a bullet wound to the leg and will be taken to jail once well enough.

Speaking at the same press conference, FBI agent Michael Schneider said it was still "premature to draw any conclusions" about Alissa's rampage's motive. Schneider added that the FBI would "make sure this suspect has a thorough trial." Alissa has been charged with ten counts of first-degree murder.

The shooting was the second deadly mass shooting to hit the US in just over a week. A gunman in Atlanta, Georgia, shot up several Asian massage parlors, killing eight people. In recent history, Colorado has played host to some of the US' deadliest mass shootings, including the 1994 Columbine school shooting, in which 13 people were killed, and the 2012 Aurora movie theater massacre, which left 12 people dead.