HOUSTON – All the Greenpeace protesters who forced the closure of the Fred Hartman Bridge have been arrested. Officials said the 23 people who took part in the act are facing several possible charges. The Harris County District Attorney's Office is determining what those charges will be.

Authorities said the Fred Hartman Bridge and the Houston Ship Channel are open and back to normal following the protesters' arrests.

The environmental activists used colorful banners as 11 protesters hung suspended over the Houston Ship Channel. Twelve more protesters acted as spotters on top of the bridge. None were from the Houston area, according to authorities.

According to the group, the activists were protesting fossil fuels and initially planned to stay on the bridge for 24 hours.

PHOTOS: Greenpeace protesters hang from Houston-area bridge

Full Screen 1 / 16 Greenpeace protesters dangle from Fred Hartman Bridge on Sept. 12, 2019.

According to Harris County Sheriff Ed Gonzalez, the group caused an accident when they suddenly stopped on the bridge. They then rappelled over the side in an apparently premeditated act.

Gonzalez said some protesters were not prepared for the Texas heat and were in distress.

The group highlighted the fact that the protest coincides with the third Democratic presidential candidates' debate at Texas Southern University on Thursday night.

Greenpeace protesters dangle from Fred Hartman Bridge WATCH LIVE: Arrests made as 11 Greenpeace protesters dangle from Fred Hartman Bridge in Houston MORE --> https://www.click2houston.com/news/local/greenpeace-protesters-hang-from-fred-hartman-bridge Posted by KPRC2 / Click2Houston on Thursday, September 12, 2019

Gonzalez said the hanging protesters were brought down one by one.

He said most of the protesters were cooperative while they were being taken into custody. Gonzalez said the ones who were not cooperative were not combative, they just didn't comply with commands. All 12 spotters were arrested peacefully, the sheriff said.

Deputies have begun placing protestors on the Fred Hartman Bridge into custody and placing them under arrest. The operation is ongoing. #hounews pic.twitter.com/vUYxySDB9C — HCSOTexas (@HCSOTexas) September 12, 2019

Authorities said the major concern was the safety of the citizens and protesters.

The bridge was closed for hours as the protesters were arrested. Gonzalez said it took a while to assess the situation because they had to evaluate the safety of the group's rope system and determine if they had anything dangerous in their bags, and also had to figure out how to get them down safely since they were tethered to each other horizontally.

"If we could have removed them in the first hour, we would have," Gonzalez said.

Officials said the ship channel was also temporarily closed because protesters threatened to lower themselves to stop ship traffic.

Authorities said they had no prior knowledge of the protest.

U.S. Rep. Brian Babin, R-Texas, called on state officials to remove protesters if local authorities didn't.

"If the HCSO will not uphold the law and put a stop to this right now, I call on the Governor and other state officials to bring in the Texas Rangers to put an end to this and resume commerce on the ship channel," Babin said in a written statement.

Drivers

Drivers said that politics aside, the protest created major traffic issues for them.

Michael Eicher said he couldn't get to work because of the lane closures.

"It's a nightmare out here," he said.

"People got things to do and places to be," Eddie Campbell said.

Others said they were concerned about the protesters' well-being.

"I don't think it's very safe at all," Sheldon Thibideaux said. "They could fall off at any time, and that's a long fall."