Leaders of 400 Massachusetts teachers vowed to remain on the picket line Thursday despite a state back-to-work order as strikes by teachers in six states disrupted the start of the school year for more than 100,000 students.

"We would really like to get this thing settled, but we are determined to stay out until we get a contract," James Cassidy, president of the Peabody Federation of Teachers, said Wednesday night. "As soon as they offer us a decent settlement, we'll go back to work."The Massachusetts Labor Relations Commission ordered the 400 striking Peabody teachers back to work after finding Wednesday night that the walkout violated a state law against strikes by public employees, spokeswoman Anne DeSouza said. She said if teachers did not return, the commission would pass the order on to Superior Court for consideration.