Story highlights 12 people injured in clashes outside US Embassy

Activists were protesting against US ties, during President Duterte's trip to China

Hong Kong (CNN) Anti-American protests outside the US embassy in the Philippines capital of Manila ended violently on Wednesday when a police van repeatedly plowed into the crowd.

29 people were arrested, police told CNN. They have since been released. 12 people were injured in the protests.

The incident -- which was caught on video -- came as new Philippines President Rodrigo Duterte visited China to strengthen ties with Beijing.

About 1,000 members of a self-described "newly-formed alliance of national minorities" were protesting the Philippines' "unequal relations with the US, while supporting Duterte's independent foreign policy," the group said in a statement.

A police van runs over protesters during a protest in front of the US Embassy in Manila.

Police said the protesters didn't have the proper permit to gather outside the US embassy, according to CNN Philippines. Authorities said they tolerated the demonstrations at first but stepped in when protesters got too close to the building.