All flights in and out of London City Airport were cancelled Monday after a 500-kilogram (1,100-pound) unexploded World War II-era bomb was found nearby in the River Thames.

The Metropolitan Police service cleared an area within 214 meters (700 feet) of the bomb, including several residential streets, as officers worked with specialists from the Royal Navy to remove the device, reports the UNB.

Police said the bomb was discovered Sunday at the George V Dock during pre-planned work at City Airport. They described it as a 1.5-meter (5-foot) shell that was lying in a bed of dense silt.

‘The first stage of the removal operation is to free the shell from the silt so that it can be floated for removal,’ police said in a statement.

Local officials offered emergency accommodations to residents and said work to remove the bomb would continue into Tuesday.

Airport CEO Robert Sinclair said he recognises that passengers will be inconvenienced but said the airport is cooperating fully with authorities ‘to resolve the situation as quickly as possible.’

London City, the smallest of London’s international airports, handled 4.5 million passengers last year. Popular with business travelers, it’s located in east London’s docklands, an area that was heavily bombed during World War II.