Greenpeace activists stage protest on Fred Hartman Bridge

BAYTOWN (FOX 26) - Greenpeace protesters have been safely lowered from the Fred Hartman Bridge after spending several hours suspended by ropes and harnesses over the Houston Ship Channel, authorities say.

The activists were suspended from the bridge to protest the use of fossil fuels ahead of the Democratic debate Thursday night in Houston.

Greenpeace USA wrote on Twitter Thursday morning, "BREAKING: We're in Houston shutting down the largest oil export channel in the country to resist Trump & the oil industry for fueling this #ClimateCrisis. It's time to end the age of oil. #PeopleVsOil"

RELATED: Third national Democratic debate tonight at Texas Southern University

Eleven protesters were suspended from the bridge, and more were stationed at the top.

Around 3 p.m., the sheriff’s office said deputies were arresting the protesters on the bridge. Firefighters from the Baytown Fire Department and Houston Fire Department then repelled down to the suspended protesters and lowered them into boats stationed below.

“It’s been a very difficult and complex situation. This isn’t an everyday kind of occurrence for us. We’re talking about significant heights, wind factors, traffic, also the unknowns as well. We couldn’t do any medical surveillance based on where they were positioned very closely. We didn’t know what was in some of their bags. And a lot of other safety factors that we’re concerned about beyond just any protest of whatever cause it was,” Sheriff Ed Gonzalez says.

Sheriff Gonzalez says all of those factors were taken into consideration, and when it was safe enough to begin attempting a safe operation, they began arresting the protesters.

Just before 10:30 p.m., the sheriff’s office said all the protesters had been safely lowered from the bridge.

The Coast Guard closed a portion of the Houston Ship Channel on Thursday morning due to the protest, but it has now been reopened.

“Our partnerships with federal, state and local agencies as well as stakeholders allows us to quickly respond to any maritime safety concerns and mitigate impact to the waterway,” Capt. Richard Howes, Sector Houston-Galveston deputy commander, said in a statement. "The work of the Harris County Sheriff's Office greatly supported the Coast Guard's efforts to reopen the waterway to vessel traffic."