A train derailment in Montana caused a bridge across the Yellowstone River to collapse and sent multiple cars into the water below, officials in Stillwater County said Saturday.The derailment occurred around 6 a.m. Multiple tanker cars were damaged and are leaking "petroleum products," according to Yellowstone County Disaster and Emergency Services.Yellowstone County officials said there was no immediate threat and "precautions are being put in place."The cause of the derailment has not yet been determined and people are being asked to keep away from the areas around the Yellowstone River Rail Bridge."Local fishing accesses will be closed. Water treatment plants, irrigation districts, and industrial companies are taking appropriate precautions," the Yellowstone County Sheriff's Office said.The Yellowstone County Disaster and Emergency Services has asked people living in the area to conserve water.Tammie Mullikin, a spokesperson with Stillwater County Disaster and Emergency Services, said notifications have been made to all required agencies, and "safety and hazard mitigation efforts" have been implemented in response to the incident."We have formally established a unified command and are using the incident command system," Mullikin said. "Unified Command is working together to determine the most appropriate steps to ensure a safe resolution to this incident."Montana Gov. Greg Gianforte tweeted Saturday that he was monitoring the derailment. "The state is standing by to support as Montana Rail Link and county officials assess their needs," he said.CNN has reached out to Montana Rail Link for additional information.