The American Red Cross is continuing to operate four shelters across three communities as officials work to check gas meters and get residents back in their homes following a series of explosions and fires that rocked the Merrimack Valley Thursday.

They are: Parthum Elementary School, 255 East Haverhill St., Lawrence; Arlington Middle School, 150 Arlington St., Lawrence; North Andover High School field house, 430 Osgood St., North Andover; and the Cormier Youth Center, 40 Whittier Court, Andover.

Deb Duxbury, Red Cross disaster program manager for the Merrimack Valley territory, said the organization planned to keep its shelters open through Sunday, and is providing food and water to those seeking refuge across the four locations, and at the main emergency command center in Lawrence.

Some 18,000 homes and businesses remain without power across the three communities.

“We’re thinking we need to be in sheltering mode until all the cities are back up and running,” including restoring power and gas service, Duxbury said.

According to a Red Cross count, three homes in Lawrence exploded and between 40 to 50 homes in the city were affected by fires, some of them major, Duxbury said. About 25 homes in Andover were affected by fires, and about 15 homes in North Andover, she said.

“We can’t do damage assessment until we’re allowed to go into these neighborhoods,” she said.

The Red Cross is also coordinating clothing donation efforts with local nonprofit Debbie’s Treasure Chest. Businesses or individuals seeking to donate water, hand sanitizer, paper towels or similar supplies can bring them directly to the four shelters, Duxbury said.

The MSPCA at Nevins Farm in Methuen is also offering free shelter to animals in need. Spokesman Rob Halpin said at one point there were 20 dogs, 13 cats and a parrot taking refuge at the animal shelter and adoption center. By 11:15 Friday, the count had fluctuated to include 18 dogs, 17 cats and the parrot.

“We are expecting more animals today and have relief staff coming from our two other shelters in Boston and on Cape Cod to help,” Halpin said.

Anyone seeking emergency shelter for their animals can call Nevins Farm at 978-687-7453 ext. 6101. After 5 p.m., call the MSPCA’s 24/7 emergency hospital, Angell Animal Medical Center, at 617-522-7282.

Follow Lisa Kashinsky on Twitter @lisakashinsky.