The U.S. Air Force said Sunday a B-52 bomber carrying six crew members crashed off the island of Guam.
The Coast Guard said two people were recovered from the waters. Their conditions were not immediately available.
Rescue crews from the Navy, Coast Guard and local fire department are searching for the others.
Officials said the crash occurred about 40 kilometres northwest of Apra Harbor.
The accident is the second for the Air Force this year on Guam. In February, a B-2 crashed at Andersen Air Force Base in the first-ever crash of a stealth bomber. The American military estimated the loss of the aircraft at $1.4 billion.