A Muslim bus driver stunned passengers by pulling over mid-route and beginning to pray in the aisle.
The driver stopped the bus without warning before removing his shoes and, using a fluorescent jacket as a prayer mat, beginning to chant in Arabic.
Passengers said they feared the driver could be preparing for a terror attack.
No one was able to get on or off the vehicle during the five-minute prayer session.
Passenger Gayle Griffiths complained to Transport for London about the bizarre incident on the No.24 bus in Gospel Oak, north London, this week.
Mother-of-one Miss Griffiths, 33, of Camden, north-west London, had boarded the bus a few minutes earlier on her way home from work.
She says that she even feared at the time that the driver might be a fanatic planning to blow up the bus.
She said: 'I have done the journey a million times before but I was in a hurry to get home to pick my little girl up from school.
'We had just picked up and let off people at a bus stop and moved off again when the driver stopped the bus very suddenly.
'He got out of his cab, leaving the engine running, and walked towards the middle exit door.
'He laid out a fluorescent jacket on the floor and I thought that somebody must have been sick and he was covering it up.
'I didn't really think much of it.
'But then he took off his shoes and began praying. I was gobsmacked and quite bewildered.'
Miss Griffiths said the bus driver didn't give the passengers any explanation as to what he was doing.
'He hadn't addressed the passengers at all,' she said. 'I didn't say anything and nor did anyone else. I thought it would all be over in 30 seconds but it went on for over five minutes.
Passenger: Gayle Griffiths
'It even went through my mind that this might be some sort of terrorist attack with the bus blown up because I had heard that suicide bombers prayed before attacks.
'As the engine was running anyone could also have got in the cab and driven off with a bus full of passengers.
'He was also blocking the exit, so if something had happened we would not have been able to get off.
'Everyone was looking round in a mix of shock and amazement. It was truly bizarre, ludicrous and aggravating.
'We are delayed often enough as it is in London.
'We live in a multi-cultural society but there is a time and a place for prayer and the middle of a journey with a busload of passengers is not it.'
Transport for London said it had apologised to all the passengers for the delay to their journey and said all Muslim drivers are being reminded that they should pray during statutory rest periods rather than hold up services.
A TfL spokesman said: 'A route 24 bus was delayed following a decision by the driver to stop the bus to pray.
'The bus company, London General, has had a word with the driver as this is not something that should be happening.
'TfL apologises to passengers for any inconvenience this may have caused them.
'We understand that there is some flexibility in the Muslim faith as to the times of day that drivers can pray.
'TfL and the individual bus operating companies acknowledge and value the diversity of their staff.
'As diverse employers, TfL and the bus operators provide suitable prayer or quiet rooms at garages and other key locations for staff who wish to practise their faith.
'We have asked London General to remind drivers who have a requirement to pray to use these facilities during their rest periods.'
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