A railcar leaking toxic chemicals sent plumes of gas into the air and forced the evacuation of more than 6,000 people for five hours. There were no injuries. Fifteen hours after the leak was discovered Sunday morning, officials still were not certain of the contents of the leaking tanker, but they were pumping it into portable tanks and were letting people return to their homes. The area downwind of the leak was evacuated because of fumes from the spill, Fire Chief Steve Foote said.