Derry residents return to their homes after alert
Residents in Londonderry who had to leave their homes following reports of a loud explosion in the Waterside on Tuesday have been allowed to return.
Homes were evacuated in the Spencer Road and Fountain Hill areas.
Police have said the Spencer Road reopened at 13:00 GMT on Wednesday.
They have also said that Fountain Hill and Moore Street has reopened. Police searches in the area over the coming days will focus on the car park at the Quarry Steps behind Spencer Road.
PSNI Superintendent Chris Yates said one line of inquiry is that the incident was an attack on police and they are investigating reports of masked men being seen in the area around the time of the incident.
Supt Yates said the explosion was heard all over the city on Tuesday.
"It shook houses, shook windows and was heard as far as City of Derry Airport, which is 10km away.
"There are reports that a lorry blew its tyre at around the same time. It is a possibility but would that sort of incident cause the shockwaves and noise that was felt? I doubt it.
"There are also reports that a gas cylinder exploded. That is a possibility we need to look into.
"What we also have is reports of masked men who made off from Dunfield Terrace. There are reports of debris landing on top of buildings. There were police officers in the area at time. We are not entirely sure what happened and we are just being very careful."
Supt Yates said officers were carrying out routine policing in the area at the time but there are "sensitivities" around what they were doing.
"It is a confusing picture as to what exactly happened. No-one has been able to phone us up and say 'this is where it happened'.
"We need information. Anybody that saw anything suspicious can help us."
Police have asked anyone discovering suspicious objects not to touch them but to contact police immediately.
Felicity McCall lives in the area and heard the explosion.
"It was extremely loud. It was like a flash-back in time. Immediately neighbours were at their doors. People felt it was some sort of explosion."
SDLP councillor Martin Reilly said there was "still a lot of confusion as to what the cause of the explosion has been".
"What is perfectly clear is that it has caused significant disruption to all those along Spencer Road and other parts of the Waterside," he added.