Three weeks after Hurricane Maria hit Puerto Rico, many people are heading to various locations in the mainland U.S. — including Boston, thanks to recently resumed flights out of San Juan via Cape Air.

CEO of Cape Air Dan Wolf said the company resumed passenger and relief flights to Puerto Rico nine days ago and is operating about three round-trip flights per day. Much of the island still has no power or water and desperately needs medical supplies.

 “This is one out of every 100 U.S. citizens in a very densely populated area without access to food, water and medical supplies,” Wolf said. “It is a crisis. Our ability to operate a flight should not be interpreted as a return to normalcy there. It is still a critical situation.”

Wolf said most of Cape Air’s flights so far have been half full but did not speculate on why this may be. He added that if demand increases, they will consider adding additional flights.