A 12-year-old boy made his way through security and onto an L.A.-bound flight without a ticket or boarding pass at Heathrow Airport, raising security concerns for the major international hub.

Unidentified and unaccompanied, the child was only halted when cabin crew attempted to direct him to his seat on the aircraft. When they discovered he had no flight documents, all passengers were asked to disembark for an additional security check.

"We are working with our police colleagues and British Airways to understand how an unauthorised passenger boarded the incorrect aircraft," said a spokesperson for Heathrow. "The individual did not represent a security risk and, purely as a precaution, the aircraft in question was re-screened and has since departed."

The boy, who is believed to be Dutch, did not cooperate with flight attendants when he was asked to leave. He was therefore removed by law enforcement, delaying the flight for over four hours.

"The boy would not speak to the cabin crew and they were asking if anybody spoke Dutch," said Rachel Richardson, a member aboard the flight. "He would not help them understand where his bags were so the whole aircraft had to be cleared."

British Airways believe he arrived at Heathrow as a transit passenger, and police are investigating how the boy slipped through the cracks.

Heathrow released a statement shortly after the incident to assure fliers that security is their top priority.

"We have apologized to our customers for the delay to their flight after an issue during boarding," they said. "We are assisting the police with their inquiries."