There was no shooting but a firework had been thrown into a group of people. Fourteen people were injured in a stampede.
The government declared a curfew and said it had shut down access to major social media sites and messaging services.
Installations generally forbid anyone from carrying a firearm — even if it is government-issued.
Quarterback Patrick Mahomes overcame costly interceptions to lead three fourth-quarter touchdown drives as Kansas City beat the 49ers, 24-20, for its second NFL title.