S.America Round-up: Uruguay hit by more violence
Colombia also suffered as Atletico Nacional fans fought among themselves during the derby with Independiente Medellin.
Defensor Sporting's 1-0 win over Penarol ended in ugly scenes when supporters of the losing side attacked rival fans.
Media reports said that Penarol fans insulted and hurled assorted missiles, including stones and plastic bottles, at a group of women and children who were leaving the Defensor section of the Centenario stadium.
The daily newspaper El Pais said some victims ran to the Defensor dressing room for protection and an 11-year-old boy was injured.
Penarol fans also clashed with mounted police outside the stadium and the clash ended with 10 arrests and six injuries.
The 2008/09 championship has already been suspended three times, once because of crowd trouble, once over security fears at a Penarol match and once by a players' strike.
Rodrigo Mora scored the only goal to keep Defensor top of the 2008/09 championship's second stage.
Stalemates prevailed during the weekend's round of derby matches.
Defending champions America and Deportivo Cali drew 1-1, the Bogota derby between Millonarios and Santa Fe ended in the same score while Atletico Nacional and Independiente Medellin played out a goalless draw.
The Medellin derby was marred by more crowd trouble when rival factions of the Atletico Nacional support fought amongst themselves at the Atanasio Girardot stadium during the first half.
Riot police stepped in and eventually stopped the fighting without the game having to be halted.
Chile international Gary Medel played his first match for Universidad Catolica since suffering a car accident in January when his vehicle collided with a crash barrier on the Vina del Mar to Santiago highway.
Medel, who in 2007 was arrested for drink-driving and banned for six games for spitting at an opponent, came on as a substitute in the 56th minute of the 1-1 draw at home to Everton.
Defending champions Colo Colo slumped to a 5-2 defeat at leaders Union Espanola, where David Ramirez and Manuel Neira scored twice each for the hosts and Gustavo Canales added the fifth.
Universitario beat arch-rivals Alianza Lima 1-0 in their derby when John Galliquio headed in Nolberto Solano's free kick in the 52nd minute.
Solano's team are unbeaten in six games and one point behind surprise package Juan Aurich, who stayed top of the championship's first stage with a 3-2 win at home to Alianza Atletico.