(CNN) -- Nearly 40 homes and businesses in three Massachusetts towns on Thursday suffered explosions or fires that may have resulted from an issue with gas service, officials said.
Suspected explosions have set structures on fire across dozens of blocks and forced evacuations in Lawrence, Andover and North Andover, Massachusetts State Police said.
Five patients were in unknown condition at Lawrence General Hospital, according to spokeswoman Jill Halsey.
A middle school in North Andover and a senior center in Andover were set up for evacuees, according to the agency. Andover officials asked residents and businesses in gas-serviced neighborhoods to evacuate.
Lawrence Mayor Dan Rivera estimated there are between 20 and 25 fires across the city, according to CNN affiliate WCVB.
"Incidents are across a wide swath of dozens of blocks across Lawrence and North Andover," state police said via Twitter.
Residents of the towns of Lawrence, North Andover and Andover who have service from Columbia Gas "should evacuate their homes immediately," state police said.
Gas lines were being depressurized by the company.
The state police some neighborhoods were evacuated because of gas odors.
There was no immediate information available about the extent of the damage.
"Far too early to speculate on cause" of the explosions, authorities said.
The National Transportation Safety Board is gathering information.