Police in Mexico say members of a drug cartel blocked off at least 13 major roads in Monterrey on Saturday.
Drivers were dragged out of their vehicles by armed men and their cars used to cut off the roads in the north-eastern city.
The blockade happened after a shootout between the Mexican army and alleged members of a drug cartel, in which four people were killed.
Police say the cartels blockade the streets as a show of force.
Security forces said the shootout happened in the south of the city, when soldiers on patrol chased two armoured cars they deemed suspicious.
One of the armoured cars crashed and its occupants opened fire on the soldiers.
Four of them were shot as they tried to flee on foot, a fifth escaped.
Local media say one of those killed was the man known as El Sonrics, the alleged local leader of one of Mexico's most powerful and violent drug cartels.
El Sonrics is said to have taken over as leader of Los Zetas in Monterrey after soldiers captured Hector Raul Luna Luna in June.
Monterrey, the richest city in Mexico and its industrial capital, has seen a sharp increase in crime since Los Zetas extended their operations there.