HONG KONG — Hong Kong police warned of serious consequences if pro-democracy protesters try to occupy government buildings, as they have threatened to do if the territory’s leader didn’t resign by today.

Tensions mounted ahead of the deadline set by students for the city’s Beijing-backed Chief Executive Leung Chun-ying to step down — part of broader demonstrations pushing for electoral reforms for the Asian financial center.

Both the Chinese government and the student protesters seemed to be losing patience after the weeklong street protests, the biggest challenge to Beijing’s authority since China took control of the former British colony in 1997.

In a reflection of growing concern in Beijing, China’s ruling party mouthpiece warned in a commentary today of “chaos” in Hong Kong, and expressed strong support for Leung in his faceoff with the protesters.

Late this afternoon, hundreds of young protesters crowded in front of the gate to the territory’s government headquarters, spilling around the sides of the huge building and across the street.