BARCELONA, Spain (AP) -- Protesters smashed bank and storefront windows with hammers and rocks and set fire to a cafe Thursday as economic protests in Spain's second-largest city turned violent.

The riots in Barcelona broke out during a nationwide general strike that closed factories, slowed transportation systems and crippled hospitals. Tens of thousands of people marched in Madrid and other cities protesting an economic plan of spending cuts and tax hikes.

Demonstrators ran past burning trash bins on the street. Some kicked in store windows and hurled stones at riot police.

Authorities arrested 176 protesters across Spain and said 104 people were injured in clashes, including 58 police officers. There were no immediate reports of serious injuries.