LMFAO was forced to stop their concert early in Honduras last night -- when a fire burned through the concert venue ... but cops believe the blaze was no accident.
According to local news reports, the fire broke out at the Coliseo Nacional de Ingenieros ... towards the end of the LMFAO concert.
The group reportedly ended their show after smoke began to fill the arena.
According to the reports, no one was killed in the blaze -- but at least 15 people were treated for smoke inhalation.
Cops told local media ... they suspect a "criminal hand" set fire to the electrical system. It's unclear if any arrests have been made.
After the show, Redfoo tweeted about the incident -- first joking, "Epic concert tonight!!!! Everybody in Honduras, we set the place on fire!!!!"
He also explained, "They told us that there was a fire when we were on stage.Then we went to the dressing rooms and there was smoke in the halls."
An hour later, he was more somber ... tweeting, "On a serious note. Hope everybody is safe from the fire tonight! love you Honduras!"