Lawrence General Hospital says it has treated four victims with fire-related injuries but did not immediately release their conditions or the severity of the injuries.
State Police say at least 39 fires erupted Thursday afternoon in the communities of Lawrence, Andover and North Andover.
Residents in those areas with homes that are serviced by Columbia gas have been urged to evacuate.
State Police say Columbia Gas crews are working to depressurize gas lines in the area. A spokeswoman for the company did not immediately return calls.
The three communities house more than 146,000 residents and are located about 26 miles north of Boston.