A fire sparked a major response in Milford early Tuesday morning.

Firefighters were called to a building around 4 a.m. after reports of smoke coming from inside. Upon arrival, crews found heavy fire conditions and upgraded the response to a second alarm.

Officials say the building posed challenges due to ongoing renovations and construction equipment. Crews had difficulty locating hidden pockets of fire throughout the structure.

The building’s only occupant was alerted by smoke detectors and safely got out without injuries.

The cause of the fire remains under investigation.