Japanese officials said two crew members were on the FA-18, and five others on the KC-130. Search and rescue operations were underway at the scene.
Six U.S. military personnel were missing following a still-unexplained mishap off the coast of Japan on Thursday involving two U.S. Marine Corps aircraft, which may have crashed in mid-air, U.S. officials said. It was unclear if US military officials were also assisting with the search.
The Marine Corps said the planes "were conducting regularly scheduled training when the mishap occurred".
A Marines statement said: "We are thankful for the Japan Maritime Self-Defence Force's efforts as they immediately responded in the search and rescue operation".
Dawson to face murder charge back in NSW
Through his duty lawyer, Mr Dawson tried to obtain bail so he could voluntarily go to New South Wales today to face court. The 33-year-old mother of two girls vanished from the couple's Bayview home on or around Saturday 9 January 1982.
Microsoft may reboot its Windows web browser again
Being a part of the Fast ring means that you get updates approximately every two weeks, which can be extremely buggy. Compare that to Google's 61 percent share and you can see why Microsoft may be more than a little concerned.
George HW Bush's service dog Sully pays touching last tribute
He died in Texas, his home state, late Friday at the age of 94 after several years of failing health. The casket will be loaded onto a plane during a departure ceremony scheduled to start at 10:30 a.m.
Early reports that surfaced on Twitter report that an F/A-18 (unspecified variant) and a C-130 crashed into the sea with a total of seven crewmembers on board.
The BBC's Rupert Wingfield-Hayes in Tokyo says that air-to-air refuelling is a hard and potentially risky flight operation, especially when done at night.
The 2 planes - an F-18 fighter and a C-130 tanker - were involved in a "mishap about 200 miles off of the coast of Japan around 2:00 am" according to a statement from the US Marines in Japan.