Story highlights Protesters want a referendum on austerity measures

Groups from civil servants to educators say they are being hurt by government strategy

Spain is in an economic crisis, with unemployment near 25%

Tens of thousands of demonstrators from across Spain filled Madrid's central Colon Plaza Saturday in a large anti-austerity protest.

Ten columns of marches converged on the plaza, some representing Spain's regions and others representing groups like civil servants.

Spain is mired in an economic crisis, with unemployment near 25%, and the government has taken belt-tightening measures to secure loans and reduce the deficit.

Some civil servants, for instance, dressed in black in a symbolic mourning over salary and vacation cutbacks, even as they are asked to work longer hours.

Jose Antonio Domingo, a tax collector for the town of San Sebastian de los Reyes, just north of Madrid, wore a black shirt with the words "we are poor and those at fault are rich."

The worst part of the reforms is the "humiliation" that civil servants face, he said. Elected officials meanwhile, appoint their political friends to town hall posts, even though they have no training to manage a local government, he said.

The protesters demanded a referendum on the government's deficit-reduction strategy of cost-cutting and tax hikes, and vow that if the government -- in power since last December -- does not authorize a referendum, they will try to hold their own.

The government says there have already been 1,900 protest in Madrid this year and the demonstrators Saturday promised a "hot autumn" of many more.

This weekend's protest showed how demonstrations in Spain have evolved over the past year. Anti-austerity protests at first were carried out by youths, and later, trade unions took the lead. On Saturday, dozens of civic groups joined the others in the plaza.

The government estimated up to 65,000 protesters in Madrid. A spokesman for the Workers' Commissions union claimed the turnout was closer to 1 million.

The protest was peaceful, though there was a moment of tension at one point as throngs of police behind metal barriers took position to protect the headquarters of the ruling conservative Popular Party, just up the street from protest speeches were being made.

Four people were arrested for refusing to show identification to police upon request, a government spokesman said.

Another large group at the protest were public school teachers, who wore green t-shirts.

High school teacher Jose Ignacio Blanco said cutbacks to education are hitting hard. On Friday in class, he said, there were 31 students but not enough desks and chairs. Four students had to stand during the class.

Saturday's demonstration comes at a difficult time for the government. A bailout of up to 100 billion euros for Spain's most troubled banks is already underway. Many experts say a bailout for Spain's sovereign debt is inevitable but Prime Minister Mariano Rajoy said publicly this week that the government has not decided on that and is closely monitoring the situation.