RCMP estimate somewhere between 5,000 to 6,000 people gathered on Parliament Hill Friday to celebrate 4/20 by smoking marijuana and calling for its legalization.

April 20, widely known in marijuana culture as "4/20," is a day when thousands of people gather for "smoke-ins" in cities across North America at 4:20 p.m.

Parliament Hill webcam showed a large group of people gathered on Parliament's large front lawn. They had earlier gathered at nearby Major's Hill Park before marching to the Hill.

Paramedics were called to the Hill by RCMP to stand by in case anyone needed help. And just after 4:20 p.m., paramedics said four people were treated for "various marijuana intoxication symptoms" including weakness, light-headedness and "tingling in extremities."

Only one person, a 47-year-old man, was taken to hospital for alcohol and marijuana intoxication. He was listed in stable condition.

RCMP Cpl. Lucy Shorey told CBC News no arrests had been made as of about 5 p.m. Friday afternoon. She said RCMP continued to maintain a presence in the area as crowds started to disperse.

The 4/20 tradition has many reputed origins, but it's believed to have originated in the 1970s at a California high school where students would gather at 4:20 p.m. every weekday to smoke pot.