The BBC’s David Ornstein reported that, while no one had been hurt, the bus was rendered undriveable after projectiles had been thrown at it.
The BBC correspondent also added that Liverpool had apologised at boardroom level, with a statement from the Anfield club also issued.
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ESPN added further detail, saying bottles and fireworks had been aimed in the direction of the bus.
"City arrived first but their bus became a target for a few missiles as it slowed to navigate the corner of Arkles Lane and Anfield Road, where most of the fans were gathered," the report read.
"A number of red flares were also let off, making visibility difficult as supporters lined the streets outside the stadium. Liverpool arrived to a raucous welcome moments later."

Liverpool condemnation

"The club condemns in the strongest possible terms the scenes which preceded our Champions League quarter-final, which resulted in damage being inflicted on the Manchester City team bus during their arrival at Anfield," read the statement.
"We apologise unreservedly to Pep Guardiola, his players, staff and officials caught up in the incident.
"The behaviour of a number of individuals was completely unacceptable and the club will cooperate fully with the authorities to identify those responsible.
"The priority now is to establish the facts and offer Manchester City whatever support is necessary."

‘That is not Liverpool’- Guardiola, Klopp condemn City team bus attack vandalism

Jurgen Klopp and Pep Guardiola also rounded on the perpetrators of the pre-match scenes.
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