A leaky water pipe was the problem behind a massive sinkhole that formed Thursday on one of Regina's busiest streets, the city says.

The hole, about four metres around and three metres deep, opened suddenly on Victoria Avenue near the intersection with Reynolds Street in the heritage area.

City crews were working on it Friday morning, and said they hope to have it fixed by the end of the day.

However, the hole blocks an entire lane, so it was slow going for eastbound traffic during the morning rush hour.