One man stabbed and another suffers serious head injuries in separate attacks by group in Perth's north

A man has been charged and two others are being questioned after an elderly man was stabbed and a 48-year-old man was left with a broken eye socket and skull fractures in two separate attacks in Perth's north.

Police say the first victim, a 75-year-old man, was sitting in his car at Hillarys Boat Harbour around 1.40pm yesterday when two men got in and asked for a cigarette lighter, before stabbing him with a knife, inflicting serious injuries to his face and arms.

The pair then fled with another man.

Just 15 minutes later in Sorrento, the second victim was unloading sand from his ute when one of the men assaulted him.

Police said a 23-year-old was arrested nearby and has been charged with grievous bodily harm and aggravated grievous bodily harm, while the two other men are being questioned.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.