Firefighters tackle a fire engulfing residential buildings at Wang Fuk Court in the Tai Po district of Hong Kong on Wednesday.

An apartment complex in Hong Kong’s Tai Po neighborhood caught fire just before 3 p.m. local time, killing at least 13 people and injuring 15 others.

Here’s what we know so far.

Firefighters battling the flames are struggling to reach trapped residents: Temperatures are scorching hot inside Wang Fuk Court, where firefighters are struggling to reach many people still trapped on higher floors of several buildings, a fire official said.

Thousands of people affected: Wang Fuk Court, a public housing estate consisting of 8 high-rise towers and nearly 2,000 apartments, is home to almost 4,000 people. Many of the residents are pensioners, with roughly 36% of residents 65 or older, according to government-sourced data. Those who have evacuated won’t be able to go home tonight, and must find another place to sleep. One evacuated resident told CNN no fire alarms went off in her home.

Plumes of smoke and falling materials: Residents and bystanders have watched in horror as the fire continues to rage, with black smoke engulfing several of the buildings. The complex’s bamboo scaffolding – a common construction material in Hong Kong – has been peeling off the sides of the towers and dropping 10 to 20 stories down, sometimes hitting debris and sending off a shower of sparks.

Fire is rare disaster in Hong Kong: The blaze has been declared to be level five fire, the highest rating used by Hong Kong firefighters in one of the most densely populated cities with the highest concentrations of skyscrapers in the world. Hong Kong though has retained a strong track record on building safety, thanks to its high quality construction, strict enforcement of building regulations and public adherence to shelter warnings.

CNN’s Jerome Taylor, Jessie Yeung and Ivana Kottasová contributed to this post.