Aya Hishmeh is on trial, charged with murdering 17-year-old Jacob Cummins and attempting to kill four others in 2017.

A driver accused of murdering a teenager and injuring four others by deliberately running them down in an act of vengeance has cried while testifying in a Perth court, describing how she failed to find a pulse on the boy.

Aya Hishmeh, 23, is on trial in the WA Supreme Court charged with murdering 17-year-old Jacob Cummins and attempting to kill Robert Bell, Augustine Janga, Mark Kickett and Anwre Ige in Canning Vale in December 2017.

Ms Hishmeh took the stand on Monday and wept through much of her testimony, as her lawyer Anthony Elliott repeatedly paused to give her time to compose herself.

She admitted she had been fuming when she learnt her younger brother and sister had been attacked but claimed her anger had weakened by the time she got behind the wheel of her car with her then-fiance.

“I just wanted to shout at them and tell them to stay away from my family,” Ms Hishmeh said.

Asked what was the point of her accelerating towards the boys, she replied: “I just wanted to get there. I don’t know.”

Ms Hishmeh insisted she meant to stop her car near the teenagers, who were walking on a footpath, but accepted her driving had been at the very least careless.

“Everything happened so fast,” she said.

Ms Hishmeh said one of the boys had gone through the windscreen. “I thought he was dead,” she said.

“I just remember his eyes were closed.

“I just stared at him for a little while and then he opened his eyes … I told him I didn’t mean it.”

Ms Hishmeh then got out of the car to check on the other boys, including Jacob, who was lying in a bush.

She said she felt his wrist and neck for a pulse but was unsuccessful.

“I just started to panic,” she said.

Ms Hishmeh called out for help and waited for police and ambulance officers to arrive.

“I was in shock. I was just scared. I didn’t know what was going on,” she said.

The trial continues.