Police called twice before fire at The Westway Stafford
Police say they went out to two reports of anti-social behaviour at a disused pub before it was engulfed by flames.
The cause of the fire at The Westway, in Highfields, Stafford, is thought to be "suspicious", says Staffordshire Fire and Rescue Service.
Families were evacuated from nearby homes and police set up a cordon at about 18:45 GMT on Monday.
Around 40 firefighters tackled the blaze at its height and some remain at the scene to damp down.
Police were first called to reports of anti-social behaviour near to the pub, just after 16:20 GMT.
The calls related to the building being insecure and unknown people being inside, said Staffordshire Police.
Officers found no-one at the building and asked the company responsible for the premises to go and secure it.
But when the company got there police were called back due to more anti-social behaviour in the area.
When they arrived officers found smoke coming from inside the pub and called the fire service.