A firework was set off inside a mailbox at a Stephen Mather Road home Aug. 2, Darien police said.

The homeowners called police after they noticed their mailbox was charred and that some type of explosive had detonated inside, according to the report.

Police went to the scene and concluded the explosive was a firework. The complainants said the incident must have taken place some time between 4 p.m. Aug. 2 and 6 p.m. Aug. 3, police said.