A motorist who ploughed into a lollipop lady and a group of children outside a primary school during a coughing fit has been found guilty of driving without due care and attention.

Karin Williams was helping children cross the road when Robert Bell's car crashed into them. Five children and four adults including Williams were hurt.

Bell's defence argued he was having a severe coughing fit that led to him fainting before the car veered across the road and flipped over on a speed bump outside Rhws school in Rhoose, Vale of Glamorgan, south Wales.

District judge Bodfan Jenkins agreed Bell, 62, had been coughing – but not badly enough that it caused him to pass out. He said: "You failed to deal with it properly. Your misjudgment had horrendous consequences. This is a tragic case for all those involved."

Bell was fined £100, given four points on his licence and was ordered to pay costs of £1,130.

During the trial, Cardiff magistrates court heard that Williams, 50, deliberately stepped in front of the car with her lollipop sign to take the impact. She was left with broken legs, a fractured elbow, shoulder and ribs.

Four girls and a boy aged between five and 10 were left with injuries including a fractured skull, bleeding on the brain and broken bones. One girl aged 10 spent three days on a life support machine, has undergone a series of operations and still does not have use of her left arm.

Williams – a lollipop lady for 10 years and a mother of one – described hearing a "revving noise" and saw Bell gripping the wheel with his eyes wide open seconds before the crash in June last year.

She said: "I was at the crossing when all of a sudden I looked to my left and I saw a dark car coming towards me at speed. It was on the wrong side of the road and collided with a bollard. It was very close to me.

"I remember seeing the driver's eyes were wide open and gripping his hands tight on the steering wheel. It was all happening so fast. I was shouting something to warn the kids and moved in their direction out of instinct.

The next thing I remember is being underneath the car and feeling a sharp pain."

One witness told police: "It was chaos. Parents and children were screaming. The black car had been travelling at normal speed but then suddenly there was a revving noise. At the same time it veered across the road, flipped over and slid on its roof. Karin was left on the front of the car as it carried on sliding."

Bell, a retired computer consultant from Fontygarry, Vale of Glamorgan, had denied driving without due care and attention. He told police he could not remember how the crash happened. Witnesses saw him crawl out of the upside-down car "dazed and covered in blood".

Bell was heard to ask: "Did I do anything wrong? Was it my fault? Please tell me if I was speeding. Please tell me the truth."

He later said: "I saw one of the children on the floor … and blood was coming out of their mouth. The blood ran from the pavement to the gutter."

During the trial, respiratory expert Professor Alyn Huw Morice said the evidence pointed to Bell having fainted due to a coughing fit – which causes around 25 road deaths a year.