Hong Kong's pro-Beijing leader and the city's police chief visited a mosque on Monday that was struck with blue dye from a water cannon during the latest bout of violent protests.
The entrance to the Kowloon Mosque, the international hub's largest, was sprayed by a water cannon truck on Sunday, causing anger among both local Muslims and protesters.
Police use the dye -- often mixed with an irritant -- as a way to identify protesters but it has frequently left streets and buildings daubed in a garish blue.
Video footage shot Sunday showed the truck pulling up outside the building during confrontations with protesters, pausing and then spraying around half a dozen journalists and bystanders who were gathered on the street outside.
The group, who did not appear to be protesters, was struck twice, with much of the bright blue jet painting the mosque's entrance and steps.
Police released a statement on Sunday saying the mosque was hit by mistake but did not apologise.
On Monday, Chief Executive Carrie Lam and police chief Stephen Lo paid a brief visit to the mosque, surrounded by a phalanx of security guards.
They emerged some 20 minutes later without speaking to the media.
Mosque representatives told reporters that the two had apologised for the water cannon incident and that the apology had been accepted.
The representatives also thanked worshippers and Hong Kongers who flocked to clean the mosque soon after the incident.
The original Kowloon Mosque was built in the late nineteenth century to cater for Muslim soldiers from British-ruled India.
It was rebuilt in the early 1980s and remains a centre of Hong Kong's 300,000-strong Muslim community.
Lam's office and the police did not respond to requests for comment on the visit.
A police source told AFP the commissioner did apologise and further details would be released later in the day.
Hong Kong was convulsed by another day of violence on Sunday as the city nears five months of seething pro-democracy protests.
Tens of thousands joined an unauthorised but peaceful afternoon rally which quickly descended into chaos as small groups of hardcore protesters threw petrol bombs and rocks at a police station, mainland China businesses and multiple subway station entrances.
Police responded with water cannon, tear gas and rubber bullets in clashes that lasted well into the night.