12:09 p.m. | Updated This story has been updated to include the comment from the National Labor Relations Board and other details throughout.

Thousands of school bus drivers and escorts hit the picket lines Wednesday morning, leaving more than 150,000 children scrambling to get to school.

“The ones who are really hurting are our families and children,” Chancellor Dennis Walcott told WNYC.

As predicted, he said it’s been a tough morning for students and parents, especially with the weather. But at the same time, he said families are persevering, and “each day it will get better and better, and hopefully this will not last too long.”

Some bus routes are handled by companies that do not have contracts with the striking union, Local 1181 of the Amalgamated Transit Union. As a result, the Department of Education said 3,000 of the city’s 7,700 bus routes are still running. That translates to 12 percent of routes carrying general education students and almost 39 percent of the routes serving students with special needs.

The D.O.E. also said at least four vendors reported that protesters were blocking gates at their depots. The agency said the police had to intervene so that buses could leave.

Walcott said he met with the president of Local 1181 last week but “what they’re asking us to do we cannot do. I’m not sure there is any middle ground.”

The strike is about employee protections provisions, or EPPs,that have been in place for decades. They assure drivers and bus escorts will keep their jobs if a different bus company takes over their route. The city is currently bidding out bus contracts without those job protections. Walcott and Mayor Michael Bloomberg said the city can’t include the protections because the state’s highest court ruled they’re illegal. But the union claims that 2011 ruling applied only to a select group of contracts for pre-kindergarten bus routes, not all the rest.

At a bus depot in Ridgewood, Queens, striking workers said they’re standing strong. WNYC’s Stephen Nessen reported live from the scene:

“I met Jose Santiago. He’s 41 years old, he’s been a driver for about 11 and a half years. And what he’s telling me is one, he certainly does not want to be striking. He wants to be out doing his route, it’s raining and cold out here, it’s the last place he wants to be. But more importantly this is about his job, job security. Every three years he does not want to have to worry about his job being on the line. And also he lives in the Smith houses – he lives in public housing. So every day that he’s not working is a big deal. If the strike goes on for another couple of days he’s going to have to file paperwork to get reduced rent to support his family.”

Local 1181 President Michael Cordiello said his members’ average salaries are between $35,000 and $38,000 a year. The highest paid drivers make about $30 an hour for 40 weeks of the year, but escorts (also known as matrons) make less.

“Mayor Bloomberg, Chancellor Walcott, please come negotiate with us,” he said. “Put the EPP’s back in the bid. Protect the workers that have the experience. Protect the children in New York. You can do this, please come forward and end this strike it’s in your hands”

Meanwhile, bus companies that employ the striking workers filed an injunction to stop the strike. The New York City Bus Contractors, a coalition of about a dozen bus companies, filed two complaints of unfair labor practices with the National Labor Relations Board’s regional office. The companies said they’re not a direct party to the strike because the city decided to remove job protections from its future contracts with bus companies. They also claim the union is failing to bargain in good faith, because its contract with the bus companies expired on Dec. 31 and there has been no breakdown in negotiations to warrant a strike.

Nancy Cleeland, director of public affairs for the National Labor Relations Board, said it could take up to 72 hours for investigators to determine if the bus companies’ charges have merit and if the board should seek an injunction to stop the strike in federal court.

“These can end up being somewhat complex legally” she said, of such complaints.

In the meantime, bus companies plan to hire replacement workers, but a spokeswoman said it takes several weeks to get employees trained and fingerprinted in order to work with school children.

Most New York city public school students walk to school or take mass transit. But many younger children, and those with special needs rely on yellow buses. About a third of the 150,000 students affected have special needs. These include thousands of students who attend private schools but qualify for Department of Education busing because of their disabilities.

Schools are giving out free MetroCards for children today, and for parents to accompany them in some cases. Parents can also be reimbursed for 55 cents per mile if they drive their children to school. Families of children with disabilities can be reimbursed for taxis. The route finder and other bus information is on the D.O.E.’s website.

But many say that’s still a huge logistical hurdle and schools expect lots of late students.

As for how long the strike could last, Walcott said, “it’s on the union to decide how long they’re going to stay out.”

The last school bus strike in 1979 strike went on for more than 3 months.