Several people were struck by gunfire that killed as many as three, including a police officer and a suspect, in the U.S. city of Minneapolis on Thursday, city authorities said.

Three others including another police officer and a firefighter were also injured at the scene, authorities added. Local media earlier said that as many as four were killed by the gunfire.

The motive behind the attack is still under investigation, authorities said.

The Minneapolis Police Department earlier said on social media that officers were “responding to an active incident” in which six people, two of them police officers, were “reported injured.”

“This continues to be a fluid situation,” the police department said, urging members of the public to avoid an area of the Whittier neighborhood south of downtown Minneapolis, the most populous city in the state of Minnesota.

The neighborhood is home to the Minneapolis Institute of Art and the Minneapolis College of Art and Design.

Minneapolis television station KMSP, a Fox broadcast affiliate, earlier reported that six people had been shot, including two police officers and four civilians, and that one officer and two other people were dead. The station cited unnamed law enforcement sources.

CBS affiliate WCCO-TV said the suspected shooter was also killed and a second police officer was critically wounded.

The Minneapolis Star-Tribune reported that a 28-year-old police officer was killed and another was listed in critical condition after an exchange of gunfire with the suspect. It said four other people were said to have been struck by gunshots in an area around an apartment building in the Whittier neighborhood.

The newspaper said the bloodshed would mark the first Minneapolis police officer shot and killed in the line of duty in more than 20 years.

ABC affiliate KSTP reported one officer was dead and another hospitalized, while multiple civilians were wounded by gunfire.