More New Jersey residents were ordered Tuesday to leave their homes because of air contamination from a train derailment Friday that leaked a hazardous gas.

The evacuation order imposed by officials at 4 p.m. added 100 more homes to the area of Paulsboro where people were not being allowed to stay, increasing the number of evacuated residences to more than 200.

The evacuation is expected to last until Sunday, a day longer than previously expected. Also, schools in Paulsboro are to remain closed until next week.

But Coast Guard Capt. Kathy Moore, a spokeswoman for the group of federal, state and local agencies managing the disaster response, said at a news conference in neighboring Clarksboro that the expanded evacuation means that others in Paulsboro - which has about 6,000 residents - will no longer have to stay inside.

Seven train cars derailed at an old railroad bridge over Mantua Creek; one tanker car ruptured, releasing thousands of gallons of vinyl chloride into the atmosphere. Though no serious injuries or illnesses have been attributed to the leak, dozens of people who live or work nearby were checked out at a hospital.

Moore said that the Coast Guard and other agencies hope to get the remaining 600 to 800 gallons of vinyl chloride out of the breached tanker car by Sunday by dissolving it into a liquid and pumping it out.