Bus drivers have threatened to pull out of parts of Belfast after two attacks on staff.
One driver was threatened at knifepoint while a second suffered a serious hand injury when his bus was rammed by joyriders.
The incidents occurred on Wednesday night.
A union which represents drivers has called on community leaders to help tackle the problem.
Michael Dornan, chair of Unite's bus committee at Translink, said there was a lot of anger at the attacks.
"Our members are outraged at these latest attacks on our colleagues who were out providing a service for the communities they were attacked in," he said.
The first incident occurred shortly before 9pm in west Belfast when a stolen car smashed into a bus at Suffolk Road.
The bus driver suffered a suspected broken finger, while one passenger received minor injuries.
A blue car believed to have been involved in the collision was later recovered at Falcarragh Drive.
Police said the car had been abandoned by two men and a woman.
In a separate incident, another driver was left badly shaken after a man wearing a hoodie and carrying a knife boarded a bus near Forthriver Road in north Belfast and stole the cashbox.
Mr Dornan condemned both attacks, adding that drivers were providing a valuable service.
He called upon community leaders in both areas to help identify those who carried out the attacks.
"We will not tolerate needless attacks on drivers," he added.
"If the community leaders from those areas cannot provide us with assurances of our safety while serving the people of that community, then we will pull back from that area or any area that can not control this needless anti-social behaviour, as someone could have been very seriously injured last night."
A spokesman for Translink, the parent body of Metro, condemned those responsible for targeting its staff and passengers.
"We strongly condemn all acts of violence and anti-social behaviour towards our employees and passengers," he said.
"CCTV is in operation on board our services and we are assisting the police with their investigation.
"For safety reasons, large amounts of cash are never carried on board Translink bus services and we would encourage anyone with information relating to both criminal incidents to contact the police."