A crash involving a TTC bus and a construction truck carrying a crane killed one person and left 13 others injured on Tuesday.

The crash occurred at Lawrence Avenue East and Railside Road, near the Don Valley Parkway exit, at around 2:30 p.m.

The collision left the front end of the bus completely mangled and killed a 43-year old female passenger. Six others were rushed to hospital with serious injuries and four others suffered minor injuries.

Toronto police spokesperson Const. Wendy Drummond said that investigators are attempting to piece together what occurred, but getting the details will take time.

A bad lane change could be a possible explanation for the crash.

"We don't know if (the driver) was turning because of the collision or he was steering or he saw the imminent collision coming. It's looking more and more like the bus may have been doing a lane change, (possibly) to avoid (the truck). We have to look at the difference in speed of both of the vehicles," said Const. Hugh Smith.

Witness and nearby resident Yvonne Bullard said she ran to her apartment window after hearing a loud explosion.

"I dialed 911 immediately and I told them if there is somebody sitting in the front (of the bus) I think they might be dead," Bullard said.

TTC officials conducted a parallel investigation at the scene alongside police on Tuesday evening.

One woman told CTV Toronto her adult daughter was on the bus but officials wouldn't tell her anything except that "everybody was bleeding." She said her heart went out to the woman who lost her life in the crash.

Both lanes of Lawrence Avenue East near the Don Valley Parkway were closed for the majority of the day. TTC officials also diverted several bus routes including the 54 Lawrence and the 95 York Mills.

With files from Natalie Johnson.