Juventus rallied from two goals down to draw 2-2 at Parma on Sunday as Italian soccer was thrown into disarray by the accidental killing of a Lazio fan.
Udinese beat Fiorentina 2-1 to hand the Viola their first loss of the season.
A police officer accidentally shot and killed a Lazio fan while trying to quell a clash with Juventus supporters at a highway rest stop in Tuscany, a police chief said.
The victim was identified as Gabriele Sandri, a 26-year-old disc jockey from Rome. He was traveling to Lazio's match at Serie A leader Inter Milan.
The Italian soccer federation postponed the Inter-Lazio game to a date to be determined. Sunday's other games were ordered to start 10 minutes late, with players and referees wearing black armbands.
The death prompted clashes between fans and police in Bergamo, where AC Milan were playing Atalanta. The match was suspended after seven minutes when Atalanta fans tried to break through a barrier and storm their way onto the field. It will be rescheduled at a date to be determined.
Atalanta captain Cristiano Doni went over to try to calm the fans but to no avail, and both teams headed into the locker room.
Fans at other stadiums took down their usual banners, and Torino fans entered the stadium late as a sign of mourning in a 1-1 draw with Catania.
Parma fans displayed only one banner, which read: "Death is equal for everyone."
When Nicola Amoruso scored in Reggina's 2-0 win over Genoa, he did not celebrate.
Officials were also considering postponing the Sunday night game between AS Roma and Cagliari in the capital.
Also on Sunday, Livorno beat Siena 3-2.