Teen in coma after car smashes into Perth house

A 19-year-old man is in a coma tonight after a car smashed into his home in Perth.

TAFE student Adam Mercer was asleep when the vehicle crashed into the property in Caversham about midday today.

Mr Mercer's family say the force of the crash was so powerful the teen was flung from his bed.

It took paramedics almost half an hour to pull him to safety.

The driver, a man believed to be in his 30s, allegedly attempted to walk away from the crash but was restrained by neighbours.

"'What's going on'? You know what the f--- is going on," one of the neighbours said to the driver as they made a citizen's arrest.

The driver is in police custody.