Negotiators for Pittsburgh's teachers union and school district wrapped up a marathon bargaining session late Friday night without a deal in place, but with no imminent plans for a strike.

Nina Esposito-Visgitis, president of the Pittsburgh Federation of Teachers, said the two sides made progress Friday. They will meet again this week for another negotiating session.

The union's executive committee voted unanimously Thursday to let Esposito-Visgitis call a strike if she deems it necessary. Last week, 94 percent of members of the union voted to authorize the strike.

The union is trying to negotiate contracts for its teachers, paraprofessionals and technical-clerical employees with Pittsburgh Public Schools. The two groups have been negotiating for more than a year-and-a-half.

The union last went on strike 42 years ago, with the teachers' walkout lasting eight weeks. Roughly 2,400 teachers work for Pittsburgh Public Schools, the district serves 24,000 students.