Cargo operations at the Port of Baltimore's public marine terminals ground to a halt after members of International Longshoremen's Association Local 333 failed to ratify a contract agreement with port operators. (Kim Hairston/Baltimore Sun video)

The three-day strike that paralyzed the port of Baltimore is over — for now.

Striking longshoremen agreed late Friday to resume working on the docks during a 90-day "cooling-off period" while negotiations continue on a new local contract.

Work on some ships had resumed earlier in the day after an arbitrator ordered them back on the job to load and unload container ships. Now that the union has voluntarily agreed to suspend the strike, its members also will resume work on the auto carriers so critical to the port, which has become the nation's No. 1 vehicle handler.

Observers saw the 90-day "cooling off period" as significant progress, though they noted that the two sides have not come to a fundamental agreement about several outstanding issues.

"We're unloading everything coming into the port of Baltimore," said Aaron Barnett, vice president of International Longshoremen's Association Local 333. "We've put all of our people back to work."

The 3-day-old strike had presented a significant challenge to East Coast shipping. At least one ship — the CCNI Antofagasta — sailed from Baltimore to Charleston, S.C., without unloading its cargo, even as other cargo ships waited. Automakers watched negotiations closely, wondering whether to implement contingency plans to divert vehicles to other ports.

The resumption of work should ease concerns for many in the shipping industry, said former Maryland Rep. Helen Delich Bentley, an adviser to the port and a longtime supporter of its business.

"We now have the opportunity to straighten out any and all disputes," she said, "so that the port of Baltimore will not lose any of the businesses that had threatened to leave."

The labor dispute had rankled shipping interests and threatened the port's hard-won reputation for labor peace, Bentley said.

An arbitrator ordered a partial end to the strike about 1 p.m. Friday, hours after talks restarted between representatives from the ILA and the Steamship Trade Association of Baltimore, which represents local port operators.

The strike began Wednesday morning after Local 333 members overwhelmingly rejected a contract covering local issues such as workplace safety the night before. Longshoremen gathered outside shipping terminals chanting and carrying signs that read: "No contract, no work."

Though the port's three other local unions had already agreed to local contracts, their members refused to cross the picket lines and stopped working in solidarity with Local 333.

The four ILA locals in Baltimore represent about 1,200 dockworkers, but the Maryland Port Administration says the port and its operation directly employ about 15,000 people and sustain tens of thousands of more jobs statewide.

The arbitrator's order Friday was limited to work covered by a master agreement negotiated earlier this year by the national ILA and the U.S. Maritime Alliance, which represents port operators and shipping lines up and down the East Coast.

That contract included a no-strike provision that the Steamship Trade Association said Local 333 was violating, which may have played a role in the resumption of work.

Longshoremen from all four unions went back to work on container cargo and so-called "roll-on, roll-off" farm and construction heavy equipment, said Richard Scher, a spokesman for the Maryland Port Administration.

But the ILA did not immediately resume work on automobiles or so-called "break-bulk" cargoes such as paper and forest products. The handling of such cargoes is covered by the local agreement over which Local 333 went on strike.

The union said late Friday that it would suspend its strike on those ships as well.

Barnett said mid-Friday that the parties were "making progress" at the negotiating table with the arbitrator, but declined to provide specifics as to what led to the shift.

"We want all the working men and women in the port of Baltimore to be gainfully employed; we want our customers to be happy. It's the holiday season coming up," he said.