Thousands of Mexicans marched in the capital to complain about a gasoline price increase, demonstrating a day after police in Sonora state fought a pitched, three-hour battle to free a border rail crossing blocked by protesters.

Demonstrators have been protesting across Mexico against a 20 percent hike in gasoline prices that took effect on New Year’s Day, and the anger has occasionally erupted into violence, including several days of looting last week.