Under HM-232 (49 CFR Part 174), which of the following describes the 'two-hour rule' for hazmat in train accidents?

1. Railroads must notify the FRA within two hours of any hazmat release
2. Crews must begin hazmat response procedures within two hours of a derailment
3. Hazmat containers must be inspected every two hours during transport
4. Crew members must leave the hazmat scene within two hours of arrival of emergency responders