Gunmen burst into a party in western Mexico and killed eight youths and left another person wounded on Friday.
It was the second such attack in two days. On Thursday, gunmen in the border city of Ciudad Juarez shot dead six young men and a woman at a wake, and seriously wounded a 10-year-old girl, dpa reported.
Friday's massacre occurred in the Pacific coast township of Navolato, near the Sinaloa state capital of Culiacan.
Sinaloa prosecutors' spokesman Martin Gastelum said he did not have details on the identity of the victims, but confirmed that there were eight dead and at least one wounded.
Local media reported that the attackers arrived in a convoy of vehicles and opened fire with assault rifles - tactics favored by Mexico's drug gangs.
The motive was not immediately clear. But the state is home to some of Mexico's most powerful cartels, and gunmen have taken to staging mass attacks on gatherings they believe might be attended by rival gang members.
The death toll in Thursday's Ciudad Juarez shootings rose to six on Friday after a woman died of wounds suffered in the attack on the wake, which was being held at a private home for a young man shot to death in his car earlier in the week.
In January, gunmen killed 16 people, many of them teenagers, who had gathered for a party in Ciudad Juarez.
Also Friday, marines raided a medical center in the border state of Nuevo Leon that authorities believe was used to treat wounded drug cartel gunmen.
Seven people were arrested, including medical personnel and three men with bullet wounds apparently suffered in a shootout with federal police earlier in the week.
And in the nearby city of Monterrey, marines arrested the city's chief business inspector for allegedly working with the Zetas drug gang and shaking down nightclubs for protection money.