Moab police dispatcher Ann Twitchell confirmed the explosion, but said she is unaware of any fatalities.
"Right now, all I can say is that all emergency crews are on the scene. We have at least 20 injured," she said
John Dwan, spokesman for the University of Utah Medical Center in Salt Lake City, said an Airmed helicopter was on its way to the Moab area and should arrive in two hours. Another helicopter was preparing to go.
Dwan said his hospital and LDS Hospital in Salt Lake City were on mass casualty alert but did not know how many injured to expect.
A spokeswoman at the Allen Memorial Hospital in Moab said the hospital was gearing up to accept a number of injuries.
Julie Gentz of D-Williams Companies in Tulsa, Okla., says the company was trying to confirm reports of a rupture on its Rocky Mountain Pipeline north of Moab.
The 412-mile pipeline runs from Daggett County in northeastern Utah to Bloomfield, N.M.
The police dispatcher said State Road 191 between Moab and Interstate 70 has been closed.
Moab, famous for its slick-rock bike trails, is just south of the entrance to Arches National Park and about 194 miles southeast of Salt Lake City.