A stunning disclosure in London’s River Thames constrained authorities to empty the adjacent London City Airport on Sunday, after reports said an unexploded World War II-period bomb was found.

The weapons was found at the George V Dock in North Woolwich amid booked work at the airport soon after 5 a.m. nearby time, experts said in a news discharge.

The Royal Navy “confirmed the nature of the device,” police said. Sky News and other U.K.- based news outlets revealed it was an unexploded bomb.

Police closed off a zone around the site that night as an insurance.

London City Airport tweeted Sunday that the airport has closed down while the weapons is managed, including, “Passengers are advised not to travel to the airport until further notice.”

Metropolitan Police and the Royal Navy were attempting to remove the historical thing.