Two players who wear No. 26 joined hands with the coaches of the St. Louis Rams and Minnesota Vikings in tribute to the victims of the school massacre in Newtown, Conn., and New York Giants' players wore decals with the initials of Sandy Hook Elementary School.
There were moments of silence before all NFL games Sunday. The ceremony in St. Louis included Rams coach Jeff Fisher and Vikings coach Leslie Frazier, along with Rams running back Daryl Richardson and Vikings cornerback Antoine Winfield.
The players were selected because their number represents the total slain at the elementary school on Friday.
Dozens of children wearing uniform jerseys held hands with players in a circle extending from the 30-yard lines at the Edward Jones Dome, centered on the Rams logo at midfield. Richardson, Winfield and the coaches formed an inner circle.
In Atlanta, Giants' players wore decals with the acronym "SHES" on the backs of their helmets.
"As a parent you drop your kids off at school many times. It's hard to put into words what that community and those families must feel like. We obviously kept them in our prayers," Miami Dolphins coach Joe Philbin said after his team's home game against Jacksonville. Philbin's 21-year-old son Michael fell into a Wisconsin river and drowned in January.
Flags were at half-staff at M&T Bank Stadium when the Baltimore Ravens hosted the Denver Broncos in one of the eight early games.
With the Maryland National Guard standing on the opposite end of the field from the flag bearers, the scoreboards went black as the public address announcer asked the crowd to observe "silent reflection" in the wake of Friday's "horrific tragedy."
Just before the national anthem was sung by Gatlin Brothers at Cowboys Stadium in Arlington, Texas, there was a moment of silence, which included the huge video screen hanging over the field going black. Also, the ribbon boards and other electronic signs were turned off.
In New Orleans, the Superdome fell silent for nearly 30 seconds before the Saints hosted Tampa Bay. People around the stadium removed their hats, bowed their heads and remained still until the public address announcer introduced the national anthem singer, "American Idol" contestant Skylar Laine.
In Houston, video screens went black as the moment was observed before the Texas hosted the Indianapolis Colts.
In Chicago, Green Bay wide receiver Donald Driver retweeted the names of the victims.
A moment of silence was held in Toronto before Buffalo's game against Seattle at the Rogers Centre. Players stood quietly with their heads down on their sideline while fans stood.
The Bills did continue their pregame habit of playing U2's "Sunday Bloody Sunday," which they've played before every home game this season. The song is in reference to British troops shooting and killing unarmed protesters in Derry, Northern Ireland in January 1972.