HAMBURG, Germany (AP) _ German police arrested the alleged hijacker of an EgyptAir plane after he forced it to land Tuesday in Hamburg. All 55 people aboard were freed, authorities said.

The hijacker, armed with a knife, seized control of Flight 838 shortly after it took off from Istanbul's Ataturk airport at 6:16 p.m. (11:16 a.m. EDT) headed for Cairo. The motive for the hijacking was not known.

Police overpowered the man when he came off the Boeing 737-500 onto the tarmac, said spokesman Hans-Juergen Petersen.

One of the co-pilots suffered a minor neck injury during the ordeal, Petersen said. Cairo airport sources had said the cockpit crew resisted the hijacker and one co-pilot was injured.

A second person was briefly detained as he came off the plane, and later released when it became clear he was not involved in the hijacking, Petersen said.

Passengers were led to buses to take them to the terminal. The alleged hijacker was being questioned by police, Petersen said.

The plane had been led to an area about a quarter-mile from the terminal, Dannel said. Before the plane landed, police diverted cars headed to the airport, but other planes continued to land.

The hijacked plane landed in Hamburg at 8:45 p.m. (2:45 p.m. EDT), airport spokeswoman Karin Dannel said. German police and firefighters had been placed on alert for its arrival.

In Washington, State Department spokesman James Foley said there was no indication any Americans were aboard the flight.

The hijacker had reportedly demanded the plane take him to London. But an EgyptAir official in Cairo said the pilot, Capt. Hazem Abadi, told the hijacker the plane did not have enough fuel.

Security on EgyptAir, which flies daily from Istanbul to Cairo, includes sky marshals who routinely travel on its flights and assist with pre-boarding baggage checks.

The plane had 46 passengers and seven crew members aboard, as well as two sky marshals, the airline said.

In Cairo, Flight 838 was listed as ``delayed'' and people meeting it learned of the hijacking from reporters.

Three planes have been hijacked in Turkey in the past year. Turkish authorities claimed security was beefed up at airports as a result.

Turkish airports now have more police officials and improved metal detectors that detect items as small as metal buttons and hair clips. Passengers must identify their bags on the tarmac and unclaimed baggage is not loaded onto the plane.