Bonville RFS firefighters had a lucky escape when a bushfire around Nana Glen turned ferocious due to strong winds, melting parts of their fire truck.

A teen volunteer with the Rural Fire Service in NSW has been charged after allegedly lighting seven fires in the Bega Valley area.

The 19-year-old allegedly lit a fire on Tuesday afternoon next to the Bega river, left the area and returned to fight the fire for the RFS.

He was arrested at a Tarraganda fire shed within two hours of the fire. The teen has been charged with causing the fire as well as six others since October 17, and bailed to appear before Bega Local Court on Wednesday.

A NSW Police statement said officers had seen a man sitting in a dual cab ute next to Bega River about 5.20pm on Tuesday and a short time later had seen smoke and a pile of trees and grass on fire.

Police will allege in court that the man lit the fire and left the area before returning to respond to the fire as part of his duties as a volunteer firefighters.

There have been seven fires in the Bega Valley area between October 17 and Tuesday, November 26, which are believed to have been deliberately lit.

The man has been charged with seven counts of cause fire and be reckless to its spread.

The RFS said it had immediately stood down the 19-year-old volunteer and had a “zero tolerance” approach to arson.

“Our members will be rightly angry that the alleged actions of one individual can tarnish the reputation and hard work of so many,” RFS Commissioner Shane Fitzsimmons said in a statement on Wednesday.

“This type of alleged behaviour is the ultimate betrayal of our own members, and of the broader community.”

In a separate incident, a 33-year-old man has also been charged over a fire-lighting spree which destroyed four cars in the NSW Hunter.

Police arrested the man on Tuesday after the string of fires were allegedly lit in Lake Macquarie suburbs between November 8 and November 19. Four cars were destroyed on a single night, police said.

“Acts of arson at any time of year are extremely dangerous, let alone during the high temperatures we have recently experienced,” Superintendent Danny Sullivan said in a statement on Wednesday.

The man has been charged with 12 counts of destroying property with fire and has been refused bail to front Belmont Local Court on Wednesday. Almost 130 bush and grass fires are currently burning around NSW.

— With AAP