An ambulance carrying an elderly grandmother to hospital was stuck in floodwater on Oxford's Eastern Bypass as torrential rain brought chaos to Oxfordshire last night.

Houses were struck by lightning, buildings were flooded and vehicles became stranded in last night's electrical storm.

There was traffic chaos on the northbound stretch of the Eastern Bypass, just south of the BMW plant, when an ambulance carrying Pamela Rivers, 79, of Cumnor, to Oxford's John Radcliffe Hospital got stuck in floodwater.

Mrs Rivers had felt ill after returning from holiday and her daughter Sarah Higton, 46, had been travelling with her. Mrs Rivers was transferred to another ambulance.

Traffic was backed up to the Littlemore roundabout.

HGVs were forced to wait by the side of the road on the northbound carriageway as police officers directed cars back up the carriageway.

Lorry driver Alistair Dewe, of Didcot, said: "I didn't have a clue what was going on. The traffic stopped and we were just told they weren't going to let HGVs reverse."

An Oxfordshire Fire and Rescue Service spokesman said: "There has been widespread flooding across Oxfordshire. It has just been chaos."

Mrs Higton, of Fogwell Road, Botley, told the Oxford Mail today that she and her mother arrived at the hospital at about 10.45pm, following a journey of about two hours.

She said her mother had suffered a suspected stroke and added: "The delay afterwards was incredibly frustrating, but fortunately my mum's health doesn't seem to have been affected.

"It was lucky she hadn't suffered something really serious like a heart attack.

"It was so slow on the roads -- it's amazing the weather can cause so much chaos."

There were power cuts in Oxford and Abingdon for a short time and it is understood the supply failure caused problems at a Brendan Benson concert at the Zodiac nightclub in Cowley Road.

Southern Electric spokesman Sharon Miller-McKenzie confirmed that a lightning strike after 8pm hit high-voltage equipment in Abingdon, knocking out supplies to homes in the Abingdon and Drayton areas for several minutes.

The fire service dealt with about 100 calls in a couple of hours as householders across the county reported flooding of their homes.

Fire crews were called to Sharp Laboratories, on Oxford Science Park, at 8.43pm.

The first and second floors of the laboratories were damaged by flooding, after a storm drain filled up.

A fire broke out in the roof of a detached bungalow in Edinburgh Drive, Didcot, when it was struck by lightning.

Firefighters in breathing apparatus extinguished the blaze, then used salvage kit to sheet the roof.

Manor School in Lydalls Road, Didcot, suffered flooding in the downpour.

Headteacher John Hawkins said the storm had caused a number of leaks but the school was open as usual this morning. In Harwell residents reported 26mm of rain falling in just one hour.

The torrential rain left the High Street under water, mirroring the flooding of three years ago. Lightning struck another home in Lambrick Way, Abingdon. The roof was damaged.

Roads on Oxford's Osney Mead Industrial Estate, off Botley Road, were waterlogged and a car was stuck under Botley Road railway bridge, which was flooded.

The roadworks on the southbound side of Abingdon Road were also under water. The Met Office said more than 14mm of rain fell within an hour across Oxfordshire yesterday evening, compared with the average June rainfall of about 53mm.