Police have launched an investigation into assault and alleged triad harassment of 30 drivers on a red minibus route between Tai Po and Yuen Long. The probe comes after a minibus driver was assaulted by five men in Tai Po on Tuesday. Another driver received a call from a man claiming to be from the Wo Shing Wo triad gang after the assault. A third driver was accused of being a troublemaker when a gang of youths boarded his minibus in Tai Po last week. On September 9, one of the minibuses running the route had its windscreen smashed while it was parked in Tai Po. Yuen Long district councillor Wong Wai-yin told police that the incidents appeared to be related to extortion. Yesterday, more than 20 drivers called a press conference to express their concerns over their safety after a meeting with police officers in Mr Wong's Yuen Long office. After the meeting, one of the drivers said she was too frightened to continue driving the route. She said it was the first time triads had harassed drivers on the route, which she has driven for more than 10 years. Chief Inspector Wong Yiu-wing, of Yuen Long police, said anti-triad officers would investigate the gang-related allegations, assault and criminal damage. Uniformed officers will step up patrols in the two minibus terminals in Tai Po and Yuen Long. The route between Po Yick Street and Fau Tsoi Street has been operated by 30 drivers for 20 years. Red minibus drivers set their own routes and fares. Green minibuses are run by companies and regulated by the government.