First responders rushed to the scene at 5 Irwin St. just before 11 p.m. Thursday night after receiving multiple 911 calls reporting an explosion in the area.
Winthrop first responders treated a 57-year-old woman who suffered third-degree burns in the explosion. She was transported by ambulance to Massachusetts General Hospital for treatment.
The Winthrop fire chief said the explosion caused damage to all floors.
The Fire Department and Building Commissioner deemed the building was uninhabitable due to both the damage and compromised safety devices such as smoke alarms.
Officials said 28 residents from the 14 units have been relocated to area hotels.
The cause of the explosion is under investigation by the Winthrop Fire Department and the state Fire Marshall’s Office.