Police arrested protesters in cities across the United States on Thursday as demonstrators blocked traffic in the latest attempt to escalate efforts to get McDonald's, Burger King and other fast-food companies to pay their employees at least $15 an hour.

The protests, which labor organizers had planned for about 150 cities nationwide throughout the day, are part of the so-called "Fight for $15" campaign. Since the protests began in late 2012, organizers have switched their tactics every few months.

Before Thursday's protests, organizers said they planned to engage in nonviolent civil disobedience to draw more attention to the cause — an idea that arose when 1,300 workers held a convention in Chicago this summer. In the past, supporters have showed up at a McDonald's shareholder meeting and held demonstrations.

The movement, which is backed financially by the Service Employees International Union and other organizations, has gained national attention at a time when the wage gap between the poor and the rich has become a hot political issue. Many fast-food workers do not make much more than the federal minimum wage of $7.25 an hour, which amounts to roughly $15,000 a year for 40 hours a week.

President Barack Obama mentioned the campaign earlier this week at a Labor Day appearance in Milwaukee, where he called for a higher minimum wage.

"There's a national movement going on made up of fast-food workers organizing to lift wages so they can provide for their families with pride and dignity," Obama said, as he pushed Congress to raise the minimum wage. "If I were busting my butt in the service industry and wanted an honest day's pay for an honest day's work, I'd join a union."

In a statement Thursday, however, the National Council of Chain Restaurants (NCCR) accused labor unions of using the protests to boost membership and attract member dues.

“While it is common for labor unions to stage events in order to grab media attention, encouraging activities that put both restaurant workers and their customers in danger of physical harm is not only irresponsible, it’s disturbing,” said the statement from the lobbying group’s Executive Director Rob Green. “Unions are calling it ‘civil disobedience’ when in reality, this choreographed activity is trespassing and it’s illegal.”

McDonald's said by email that the restaurant chain’s outlets were “open for business as usual and welcoming customers,” with no reports of service disruptions.

“We reiterate that these are not ‘strikes’ but are staged demonstrations in which people are being transported to fast-food restaurants,” McDonald’s said. “And, we have received reports that some participants are being paid, up to $500, to protest and get arrested.”

By late Thursday morning, however, protesters in some cities were standing in front of fast-food restaurants, chanting for higher pay and holding signs in both English and Spanish.

Union organizers told Al Jazeera that thousands of people showed up to Thursday's protests around the country, and that 120 workers had been arrested by the afternoon in New York, Chicago, Detroit, Little Rock and Las Vegas.

Pastor W.J. Rideout III, an activist with D15 Good Jobs Now in Detroit, said a group of several hundred protesters blocked traffic and shut down the drive-thru at a local McDonald's restaurant. About 50 of the protesters were arrested, he said, though there were no confrontations with the police.

"We're going to continue to expose corporations for the inhumane treatment they're giving their workers," Rideout told Al Jazeera. "We want them to understand that these jobs are not just high-school and college-student jobs, these are Mom-and-Pop jobs, survival jobs."

In Milwaukee, Democratic U.S. Congresswoman Gwen Moore was also taken away in handcuffs by police for blocking traffic at a McDonald's.

"I take great pride in supporting Milwaukee workers as they risk arrest in pursuit of a brighter tomorrow for their families," Moore said in a statement.

In New York, several people wearing McDonald's uniforms were hauled away by police officers after standing in the middle of a busy street near Times Square. In Chicago, a couple of buses unloaded a group in front of a McDonald's restaurant, where they chanted "Stand up. Fight back," while 100 people crowded on the sidewalk.

Prospero Sanchez, 32, who was at the McDonald's in New York, said the $11.50 per hour he earns making pizzas at a Domino's Pizza restaurant is not enough to support him, his wife and two kids. He started working at the same restaurant 14 years ago, when he made $5 an hour.

He said he has asked his bosses for more money, but "they said no."

McDonald’s added in its email: “We believe that any minimum wage increase should be implemented over time so that the impact on owners of small and medium-sized businesses – like the ones who own and operate the majority of our restaurants – is manageable.”

Michael Pizzi contributed reporting, with wire services