HONG KONG — A homemade bomb was detonated in Hong Kong on Sunday amid violent protests, the police said on Monday, indicating an escalation in the street-level arms race between police officers and the protesters.

The device was hidden in a bush and was triggered by a mobile phone as a police vehicle passed nearby in the Mong Kok district of Kowloon, Suryanto Chin-chiu, a superintendent of the Hong Kong police’s explosives disposal unit, said at a news conference.

The bomb caused no damage or injuries, but it was the first time such a device had been employed in weeks of clashes, the police said.

Once armed only with umbrellas to protect against rain and flying tear gas canisters, the demonstrators have more recently brandished bricks and sidewalk paving stones, as well as knives and gasoline bombs.