A man armed with multiple guns and large amounts of ammunition shot at police officers from inside a suburban Minneapolis home that was filled with children on Sunday, killing two officers and a firefighter who was providing medical aid to one of the wounded, authorities said.

A third officer was wounded in the shooting in a tree-lined neighborhood of two-story homes in Burnsville, Minnesota. The suspect in the shooting also died, officials said.

Minnesota Bureau of Criminal Apprehension Superintendent Drew Evans said there was an exchange of gunfire, and authorities were still piecing together details of what he described as a “terrible day”.

The firefighter, who also works as a paramedic, was shot while providing aid to an injured officer, Evans said. He told reporters the paramedic was a part of a SWAT team that had been called to a domestic situation at the home.

Inside, an armed man had barricaded himself with his family, including seven children ranging in age from 2 to 15, Evans said. He said negotiations lasted for hours before the suspect opened fire. He wasn’t specific on the exact amount of time, but the Minnesota Police and Peace Officers Association said the standoff lasted four hours before a SWAT team entered the home.