SUN PRAIRIE, Wis. — A major fire has broken out in a suburb of Madison, Wisconsin, after a loud boom was heard.

Witnesses say the boom around 7:15 p.m. Tuesday shook Sun Prairie. A massive plume of smoke is rising from the downtown area in the community of about 30,000 people.

Firefighters from Sun Prairie and surrounding communities are responding to the blaze.

Police have blocked off downtown streets from traffic and onlookers.

The area has several businesses including bars and restaurants.