(AP) — Police say a massive fire that gutted part of a southeastern Wisconsin meatpacking plant started when a military flare landed on the roof.

Cudahy police said Tuesday there's no indication the military fired the flare. Authorities aren't elaborating on the nature of the flare, but federal, state and local agencies are offering a $16,000 reward for information about who may have fired it. The reward is being funded by ATF, the Wisconsin Arson Insurance Council and Southern Milwaukee County Crime Stoppers.

Surveillance video from a plant camera released by local law enforcement shows a flare exploding above a building followed by a larger flash on top of the building. View the video. The flare ignited the Patrick Cudahy Inc. plant on the night of July 5.

The blaze lasted more than two days and caused an estimated $50 million or more in damages. It also prompted a temporary evacuation of thousands of area residents because of the possibility of an ammonia explosion.

Cudahy Mayor Ryan McCue said they will do everything they can to find the party responsible. Police believe the flare was fired from east of the plant on the evening of July 5. The fire destroyed approximately one fourth of the 1 million-square-foot plant. Of the plant’s 800 employees, only about 300 are now back to work.

Cudahy is a town of about 18,000 just south of downtown Milwaukee.

Source: Associated Press, Milwaukee Journal Sentinel