"This is a tragedy and a nightmare for the city of Boulder, in response we have help from local authorities, state authorities and the federal center", - AR quotes the words of the district attorney Michael Dougherty.
Six casualties were initially reported.
"We send our condolences to the affected families. Ten people died", - wrote on Twitter the head of the city police Maris Herold.
The attacker was detained.
According to the police, the suspect was undergoing treatment; experts believed that he did not pose a threat to society. The motives for the crime are currently unknown.
Earlier, the media wrote that two police officers were injured during the shooting.
The identity of the attacker has not yet been reported.
US President Joe Biden has already been informed about the incident. This was announced by the press secretary of the White House Jen Psaki.