Multiple people have been shot inside a Walmart store in Denver, Colorado, local police say.
Police in Thornton, a suburb about 16km northeast of the city, did not release any information on the number of victims and it was not clear if an assailant had been taken into custody.
In a statement, they said two men had died in the store and one woman had been taken to a hospital.
Police said it was not an active shooter scenario but it was an active crime scene.
"We've got multiple parties down, we're still trying to ascertain what their conditions are," Officer Victor Avila of the Thornton Police Department said.
Avila said police were called to the store at about 6:30pm local time, and the gunshots had stopped by the time the officers arrived.
An hour after the incident, the situation, the nature of the incident or status of the threat remained unclear, he said.
Local NBC affiliate 9NEWS reported that a woman whose son was in Walmart had told her that he had heard about 30 gunshots and was still inside.
A video posted on Twitter showed the store apparently empty except for police officers with guns drawn.
Local television images showed a number of police cars and ambulances surrounding the Walmart, lights flashing. The store is adjacent to US Interstate 25.