The game was suspended in the ninth inning after Mike Coolbaugh, 35, was hit by a hard-hit foul ball off the bat of Tino Sanchez and taken to Baptist Medical Center-North Little Rock.
Phil Elson, spokesman for the Travelers, said Coolbaugh was struck by the ball on the right side of his head, or on the forehead -- "I'm getting conflicting reports" -- and fell to the ground immediately.
According to a report posted on the Drillers' Web site late Sunday, Coolbaugh was knocked unconscious and CPR was administered to him on the field.
Sgt. Terry Kuykendall, spokesman for North Little Rock police, said Coolbaugh was still alive when he was put in an ambulance for the trip to the hospital, but quit breathing as the ambulance arrived at the facility.
"They tried to resuscitate him, but he was pronounced dead at 9:47 p.m.," Kuykendall said.
Coolbaugh played 44 games in the major leagues over two seasons, his last appearance with the St. Louis Cardinals in 2002. The Drillers' web site said Coolbaugh joined the Tulsa team's staff on July 3.
The Travelers, an Angels affiliate, led 7-3 at the time the game was suspended with no outs and a runner on first in the top of the ninth inning. Officials said a date and time for finishing the game had not yet been chosen.
Tulsa is a Rockies affiliate.