Gardai are appealing for witnesses to a drive-by shooting in which a man and three women were injured outside a Dublin pub.

The victims were among a group of people who had been attending a 21st birthday party at Hanlon's pub on the north circular road.

A 28-year old man is in a serious condition in the Mater Hospital after he was shot in the head during the attack.

Gardai say the man was known to them. 

Three women in their twenties received gunshot wounds to the legs, when the gunman fired randomly into the crowd.

Their condition is described as non-life threatening.

Superintendent David Taylor is appealing for information.