Runoff from a six-alarm fire at an Etobicoke chemical facility may have reached Lake Ontario after containment was breached due to heavy rain.

A statement from the Ontario Ministry of the Environment, Conservation and Parks said GFL, the contractor tasked to clean up the spill from the Aug. 11 fire, has deployed four boats to assess how much material made it into the lake and place additional containment measures.

"Booms have been installed in Lake Ontario. Cleanup crews are verifying established containment measures along the creeks, which are being reinforced where needed," the statement read.

The ministry said rain caused a rapid change in flow levels in Mimico Creek, resulting in a breach.

"The clean-up work in Mimico Creek continues and the Ministry is ensuring that Toronto Water and GFL take appropriate actions to contain and clean up the spilled materials and contaminated water from the fire," the statement read.

There have been concerns that the runoff from the fire at the chemical distribution facility in Rexdale would reach the lake.

Officials have not disclosed what kind of chemicals are in the spill. A video of Mimico Creek from earlier this week showed a thick brown substance flowing on top of the water. Several measures are being done to stop the spill, including placing booms, haybales, installing underflow dams, and deploying vacuum trucks to collect the oil slurry.

Coun. Amber Morley, who represents the Mimico area where the chemical plant is located, also provided an update Friday morning on the ongoing cleanup.

"GFL and Toronto Water continue to work to cleanup Mimico and Humber Creek, and the TRCA will continue sampling on the upstream and downstream Mimico site locations throughout the weekend and monitoring any impact to the watercourse or resident wildlife," a statement posted on her website read.

Meanwhile, the spill has also affected local wildlife. According to the Toronto Wildlife Centre, 90 birds have been rescued as of Thursday – 88 mallard ducks and two Cooper's hawks. Of those, 10 ducks and one hawk died.

The centre said the rescue has become much more challenging with the remaining birds flying off, and other animals scavenging dead ones and becoming sick.

"The substance is harming more species, including mammals like (the white-tailed deer) spotted drinking the contaminated water," the centre tweeted on Friday.

The cause of the fire is unknown. The company involved said earlier this week that it is "cooperating completely" with the investigation.