Six people were charged with multiple offences after a protest on Thursday at Queen's Park about mercury poisoning on the Grassy Narrows reserve — in which demonstrators dumped grey liquid outside the Legislature.

The six are due to appear in a Toronto courtroom on Friday.

Fire crews arrive at Queen's Park after grey liquid dumped in front of Legislature in Grassy Narrows mercury protest <a href="https://t.co/hfcfr5uJOT">pic.twitter.com/hfcfr5uJOT</a> —@CBCQueensPark Protesters dumped the liquid just before 10:30 a.m. in front of the steps to the Legislature. Security asked people to move back from the liquid on to the lawn and then police pushed people back farther to the south end of the lawn "for safety," according to officers on the scene.

Toronto firefighters on scene tried to figure out what the substance was, but one protester told the crew that it was corn starch with water and soluble paint.

One of the protesters told CBC News that if the spill were in Grassy Narrows "the government would take 50 years to find out what the grey stuff is."

The spill happened just before 10:30 a.m. in front of the steps to the legislature. (Mike Crawley/CBC)

Protesters were handcuffed and taken away from the scene by police.

The south lawn of Queen's Park was closed off as Toronto police, Toronto Fire and the Legislative Security Service investigated the grey substance.

A CBC News reporter saw the protestors handcuffed and taken away from the scene by police. (Mike Crawley/CBC) The legislature was not evacuated.

Mercury in waterways

In a report released in May, environmental scientists determined that there is an unknown source of mercury around where people in Grassy Narrows catch fish.

That prompted allegations there is a hidden pile of mercury barrels poisoning a northern Ontario river. Protesters charge that the mercury dumped in the waterways near the community has existed there for nearly 60 years and has never been cleaned up.

"We know that our river can be made safe," Simon Fobister, a chief in the Grassy Narrows First Nation, said earlier this year. "Are our lives worth less than others to the government?"

Thursday morning, Premier Kathleen Wynne said her government is "determined" to solve the problem.

"If I had the ability to go to Grassy Narrows with a crew and clean that mercury up I would do it tomorrow," Wynne told CBC's Metro Morning.

The challenge, she said, "is that there's been competing science. And right now there's a report that says there may actually be a way to clean up the mercury that's trapped in the sediment at the bottom of the lake and the river."

However, the science she was given as minister for aboriginal affairs years ago suggested that disturbing the mercury could re-contaminate the water, she said.

The province is committed to finding a solution, she said. Ontario's environment minister and a group of scientists are headed to the community next week, she said.

"If there is a new technique or methodology we will absolutely find a way to get that cleaned up," Wynne said.