SYDNEY - An Australian teenager is lucky to be alive, paramedics said Sunday, after he reportedly escaped the jaws of a crocodile by punching it in the head during a late night swim in a river.

The 18-year-old, named in local media as Lee de Paauw, suffered extensive injuries to his left arm after he was attacked in Johnstone River on Australia's northeastern coast early Sunday morning, the Queensland Ambulance Service (QAS) said. He had jumped into the river as a dare while "revelling with friends", QAS Cairns senior operations supervisor Neil Noble told reporters.

"He's very fortunate that he survived this incident and was able to be rescued... (he's) due to undergo surgery for extensive injuries to his arm," Noble said.

Local newspaper the Cairns Post said De Paauw escaped the croc's grip on his left arm by punching it in the head with his right arm.

De Paauw's friends' efforts to get him out of the water quickly helped him survive, Noble added.

Crocodiles are common in Australia's north where numbers have increased since the introduction of protection laws in 1971.

Crocodiles kill an average of two people each year in Australia.