A man has suffered life-threatening injuries after falling out of a tree at a march for marijuana legalization Saturday afternoon.

The man was perched about 20 to 30 metres up a tree at Queen’s Park around 4:20 p.m., as the Global Marijuana Marchunfolded below.

As the tree swayed in the wind, someone called emergency crews to rescue the man. Before help could arrive, he fell.

Paramedics arrived quickly and transported the man to St. Michael’s Hospital in critical condition, said EMS duty officer Dave Viljak.

The man’s name and age are unknown.

The march, led by pot advocate Marc Emery, kicked off around 2 p.m. with the masses converging on Queen’s Park about an hour later.

“This is my 12th year in a row going,” said attendee Dave Toms, 27. “Last year there were 20,000 people and this year there are even more.”

Organizers estimated the size of the march at about 40,000 people.

Toms, who spends his days working in an office and his nights drumming for a band, doesn’t smoke pot anymore but still supports the cause.

“If it was legal, that money could used for hospitals not gang bangers and guns,” he said. “I haven't heard any pro-prohibition argument that stands up against logic.”

In addition to hippies, everyone from hip hoppers, parents with children and elderly retirees attended the march, Toms said.

"It's an all-encompassing group,” he said.

The march was peaceful and police didn’t interfere, remaining around the periphery and keeping marchers separate from traffic.

Emery, the self-proclaimed Prince of Pot and founder of the Marijuana Party, is facing a five-year prison term in the U.S. after pleading guilty last year to selling marijuana seeds through the mail. He is due to surrender himself to U.S. authorities this month.