London City Airport was closed on Monday as military experts worked to remove a 500-kilogramme (1,100-pound) German World War II bomb found in a neighbouring dock.
The unexploded ordnance was discovered in King George V Dock, during planned works near the runway of Londonâ€™s most central airport.
British police said the 1.5-metre (five-foot) shell was â€ślying in a bed of dense siltâ€ť and removing it depended on the tides.
â€śAt this stage we estimate that the removal of the device from location will be completed by tomorrow morning,â€ť Londonâ€™s Metropolitan Police said in a statement.
Mondayâ€™s shutdown affected up to 16,000 passengers who were due to fly, although some airlines switched their flights to other London hubs.
The bomb was discovered at around 5:00am (0500 GMT) on Sunday and a 214-metre exclusion zone was imposed â€śto ensure that the ordnance can be safely dealt with whilst limiting any risk to the public,â€ť police said.
Homes within the exclusion zone were evacuated overnight and the local authority was providing residents with temporary accommodation and support.
â€śOfficers are assisting with a controlled evacuation of up to 500 people,â€ť the Newham Council local authority said in a statement, adding that a former town hall building had been opened up for evacuees.
It said specialist officers â€śhave attended and confirmed it as a German 500-kilogramme fused deviceâ€ť.
Newham Council said: â€śWork will not start on lifting and removing the device until the initial 214-metre zone is clear.
â€śWhen work starts to remove it, it is expected the exclusion zone will be extended to 250 metres and more properties will need to be evacuated.â€ť
City Airport operates short-haul flights and is located in east London, close to the Canary Wharf business district.
It is the capitalâ€™s fifth-biggest airport.
â€śThe airport remains closed this morning,â€ť its chief executive Robert Sinclair said earlier in the day.
â€śAll flights in and out of London City on Monday are cancelled,â€ť he said.
â€śI urge any passengers due to fly today not to come to the airport and to contact their airline for further information."
London was heavily bombed during the â€śBlitzâ€ť, the Nazi German air attacks of September 1940 to May 1941.
London City Airport opened in 1987 in the disused docklands. It handled 4.5 million passengers in 2017 and is mainly used by business travellers.