COLUMBIA--Aiken County deputies and state agents quickly protected several sites after a January train wreck in Graniteville just in case the collision and deadly chlorine gas spill was an act of terrorism.

It turned out the wreck was caused by human error, according to investigators. But in a report released Monday, the sheriff's office gave itself mostly high marks for the quick response in the hours after the crash, keeping the site secure and the orderly return of evacuees in the days after the crash.

The 11-page review of how the sheriff's office handled the Jan. 6 crash details both what was done right and what can be improved.

"This document will be invaluable in preparing for future incidents," Sheriff Michael Hunt said.

The crash happened when a train heading through the town about 2:45 a.m. barreled onto a side track and smashed into several parked railcars. A tanker car carrying chlorine ruptured, causing cloud of the toxic gas to spread through the town.

Nine people died as a result of the crash, and 250 more were injured.