Four people have been killed after a gunman barricaded himself inside a house in a Denver suburb with at least three hostages, according to reports.
The hostage-taker was among the dead at the home in Aurora, Colorado.
Local media reported that police used tear gas to try to get the gunman out after six hours of negotiations. He was eventually shot dead after opening fire on a police car from a window.
Police Sergeant Cassidee Carlson said: "After we arrived on scene, there were no more shots fired up until he fired at us.
"During this time he was all over the house. He moved furniture. He was throwing things. He was agitated. He was irrational."
Police believe the three other victims found when they entered the building were related to the suspected hostage-taker.
"We have an idea of who they are, but we obviously want to confirm their identities with the coroner," Carlson said.
"This is a big investigation, and a lot is entailed."
Police added that a fifth person escaped uninjured, but did not elaborate.
Police and SWAT teams had surrounded the home early in the morning after responding to a report of gunshots being fired and determining that a man was barricaded inside.
Officers had been negotiating with the man and several homes in the area were evacuated.
The hostage-taking came just two days before the preliminary trial for suspected Aurora movie theatre shooter James Holmes was set to begin.
The 25-year-old is accused of opening fire in the crowded cinema during a midnight screening of The Dark Knight Rises, killing 12 people and wounding at least 58.