People couldn't believe what they were seeing.

Around 20 teenagers were clambering up the girders of the Matapihi Rail Bridge, before leaping about 15 metres into Tauranga Harbour.

'It was quite a sight and definitely dangerous,” says the passerby who witnessed and filmed the daredevil behaviour for SunLive.

He thought it was 'crazy dangerous”, especially the diving and jumping from the top of the bridge over the walkway. And he half expected to be photographing a serious accident.

'I saw the police getting them off the bridge today, so I hope they have ended it.”

The incident comes off the back of The Weekend Sun's cover story last week, in which KiwiRail locomotive engineers warned kids about jumping from the Chapel Street rail bridge and running the gauntlet of 1000-tonne freight trains.

'Safety is KiwiRail's number one priority, for the public and our train locomotive engineers,” says KiwiRail's Katie McMahon.

'There have been fatalities of children playing on and jumping from rail bridges. KiwiRail's bridges, including those in Tauranga, have signs warning of the dangers and alerting people to the consequences of illegal trespass. This can include fines and police action.”

She says tracks are for trains, and any trespassing on the rail corridor is dangerous as trains are big, heavy and cannot stop quickly. 'It is critical for communities that people stay off tracks and rail bridges, and that children are made aware of the dangers of this behaviour.”

The Matapihi rail bridge has a dark past. Before the footbridge was built, it is claimed that the bridge claimed one life a year, or 30 lives in 33 years.