A seemingly healthy tree that caused a chaotic scene in Vancouver was rotting from the inside, officials have found.

The large tree trapped two people in their vehicles and scattered trolley wires across the street on Tuesday afternoon when it unexpectedly fell in the heart of the city.

Witnesses said they heard a loud cracking noise, and were shocked to see the tree drop across Cambie Street, taking poles and wires down with it.

“I’m pretty sure I started screaming,” said Maddy Kipling, who watched the tree fall onto two moving vehicles.

But Vancouver park staff said Wednesday a type of internal decay, called internal white crown rot, caused the 70-year-old tree to tumble.

Dozens of people had gathered around Tuesday to watch the unusual scene unfold.

“It’s definitely abnormal,” said witness Alyssa Mack-Lee. “I’m from a small town, so we see trees fall all the time, but in a city? That’s pretty crazy.”

Firefighters were hesitant to immediately intervene, as many of the fallen wires were likely still live. The trapped drivers waited for over an hour before the power was shut off and they could be freed.

Nobody was hurt, however one of the drivers described the event as “a little scary.”

With files from CTV Vancouver