Gunmen block roads in Mexico's second city

A charred truck - the remains of a blockade in Mexico's second city of Guadalajara after a dramatic shootout between federal police and suspected gang members.

Armed assailants set cars, buses and trailers on fire as they paralysed more than 20 roads across the city in the state of Jalisco.

With the attack bearing all the hallmarks of drug gangs, many suspect the blockades to be cartel related.

Jalisco's minister of public security told a news conference that locals were caught off guard by the events.

He said federal authorities did not alert local officials to the possibility of a blockade as on previous occasions.

Three police officers were wounded but no arrests have been made.

More than 55,000 people have been killed across Mexico in drug-related violence since President Felipe Calderon came to power in 2006 and declared war on the cartels.