DOHA, Qatar (CNN) -- A Tornado GR4 aircraft returning from an operational mission has been shot down by a Patriot missile near the Kuwait border, a British military spokesman has said.

The Tornado's crew members are listed as missing and investigations are underway.

"Something probably went wrong in some way, but we're in an incredibly busy environment ... with every pilot focused on what they're doing," spokesman Capt. Jon Fynes said.

Fynes said investigators will look for something obvious that can be fixed easily, but if it can't be fixed "today or tomorrow, it will be fixed."

Joint Chief of Staffs chairman, Gen. Richard Myers pointed to a possible breakdown of the "elaborate procedures and electronic means to identify friendly and enemy aircraft" as causing the incident.

"Central Command is looking into that as we speak," Myers said Sunday on ABC's This Week.

"People have to react in a hostile environment; mistakes can happen," Fynes said.

The loss of the aircraft comes after two deadly accidents involving helicopters belonging to U.S. and British forces.

Six British crew members and one American were killed Saturday in a midair collision between two British Navy Sea King helicopters over the Persian Gulf, according to the UK Central Command in Qatar and the Pentagon.

On Friday, a U.S. Marine CH-46 helicopter crashed in Kuwait, killing all 12 people aboard.

The eight British and four American dead were the first coalition casualties of the war against Iraq.