Darlene Helms has deployed to disaster zones with the American Red Cross 10 times. The eleventh might be like nothing she’s ever seen.

“We’re told to expect the unexpected,” Helms, of Hampden, said Monday as she prepared to start her journey to Puerto Rico.

Helms is leading a team of five Mainers heading to Puerto Rico for three weeks to help with disaster response in the wake of hurricanes Irma and Maria. They don’t know if they’ll have a place to sleep, three meals a day or running water.

Hurricane Maria was especially devastating to the U.S. territory, leaving much of the island without electricity, phone service and medical help. Many towns have been left without fresh water and fuel, and roads in some areas are impassable. A major dam is believed to be in danger of collapsing. The government is still trying assess the scale of the damage in many areas and has not been able to make contact with some municipalities.

The team from Maine will be in Puerto Rico for 21 days, about a week longer than typical Red Cross deployments. Larry French, disaster program manager with the American Red Cross, said the team will face an unusually difficult deployment because it is not known what conditions they will encounter when they arrive.

Relief workers are facing the logistical challenge of trying to get food, water and other necessary supplies to an island that is largely cut off from communication, French said. The Red Cross is working with federal, corporate and community partners to get supplies to the island by both air and sea.

The team members who left Monday are Helms, Anne Hemingway of Phippsburg, Crystal Abbot of Alfred and Jim Kerrigan of Old Orchard Beach. Victoria White of Lewiston is expected to join them. They each underwent six health and mental health screenings before they left, a necessity because of the tough conditions they are likely to encounter, French said.

Team members flew Monday to Atlanta, where they will do final screenings and pick up more supplies. They expect to take a military transport to Puerto Rico either Tuesday or Wednesday. Two other teams of Mainers have been assembled and will leave for Puerto Rico and the U.S. Virgin Islands in the next few weeks.

The trip to Puerto Rico is the first Red Cross deployment for Jim Kerrigan of Old Orchard Beach. He said he is between jobs and was looking for volunteer opportunities when someone suggested the Red Cross. He doesn’t speak Spanish and has never been to Puerto Rico, but he is confident he and the other volunteers will be able to help reunite families and make sure residents of Puerto Rico get much-needed supplies.

“We’re just trying to help out and making sure people have a safe place to stay and food to eat,” Kerrigan said.

Because of the uncertainty about what conditions they’ll encounter and what food and supplies will be available, the Maine team had to pack such items as toilet paper, mosquito netting, water purifiers and energy bars, Kerrigan said.

Helms, 64, returned two weeks ago from Texas, where she helped set up an emergency shelter in Galveston following Hurricane Harvey. She returns from the deployments feeling both “refreshed and drained,” but says it’s worth it to help out during a season of especially strong and devastating hurricanes.

“You help people and you see it in their faces,” she said. “It’s an amazing feeling.