ST. JOSEPH, Mo. -- Eric Berry made the first trip to the injury tent. Marcus Cooper followed soon afterward.

David and DeMarcus Van Dyke, a pair of cousins trying to earn jobs in the Chiefs defensive backfield, were already milling around it. And missing from the scene entirely was safety Sanders Commings, who was headed for surgery on a broken bone in his right foot.

Apparently, Chiefs defensive backs deserve hazard pay these days.

The biggest cause for concern was Berry, their Pro Bowl safety, who hurt himself during a drill early in Thursday's workout. He was checked by trainers in the tent before conferring with some more team officials on the sideline, and then driven in a cart to the locker room.

Berry was able to put weight on the leg, but was noticeably limping, and Chiefs coach Andy Reid said he was still awaiting word on the severity of the injury.

''It's no Achilles, it's no tear,'' Reid said. ''We'll have to see.''

Later in practice, it was Cooper who limped to the tent. Trainers spent several minutes probing his hamstring before loading him into another cart and sending him to the locker room.

Those injuries, combined with the plethora of ailments that have already besieged the Chiefs' defensive backfield, have left them perilously thin at a position that was already causing concern.

The secondary struggled against Indianapolis in last season's playoff loss, and it hardly helped matters when the team released Pro Bowl cornerback Brandon Flowers in a cost-saving move.

One of the guys they were counting on to compete for the safety job was Commings, who missed his rookie season with a broken collarbone.

He got a late start to camp following another injury, and then broke his foot when he was juked to the ground by running back Jamaal Charles in practice Wednesday. It was unclear whether the Chiefs plan to put him on injured reserve.

''We'll see,'' Reid said. ''Normally if you break a bone it takes a while.''

The Van Dykes were continuing to rehab their own hamstring injuries off to the side Thursday, which means that of the 18 defensive backs had in camp, only 13 of them were on the field by the end of practice. That included Damond Smith, who was signed just this week.

''That happens,'' Reid said of the injuries. ''It happens as you go through camp, your legs get tired. You get those strains, those tight hamstrings. We'll be fine. We'll push through it.''

With whomever they can manage to suit up.

Shortly after practice, agent David Canter announced on Twitter that the Chiefs had signed veteran defensive back Steve Gregory. He entered the league in 2006 and played with AFC West-rival San Diego until 2011, when he joined New England for the past two seasons.

Daniel Sorensen, an undrafted rookie out of BYU, moved into Berry's spot when he went down on Thursday. Jerron McMillian and Malcolm Bronson have also been spending time at safety.

''You know, tomorrow I might be running with the 3s,'' Sorensen said of his unexpected move into the starting lineup. ''That's just how it goes.''

The cornerback position was already in a state of flux even before Cooper got hurt.

Picked up off waivers last season, Cooper had moved into the starting lineup in place of Flowers, while Ron Parker had relegated veteran Sean Smith - the other starter a year ago - to the second team. Chris Owens has been working primarily as the nickel, and rookie Phillip Gaines has been getting reps at several positions as he tries to turn some heads.

''The one thing he has, he does have excellent speed,'' defensive coordinator Bob Sutton said. ''He does have that ability to make up if he gets behind guys and make plays like that.''

That ability would have come in handy last season, when Chiefs defensive backs were spending so much time trying to chase down wide receivers.

After their bye in Week 10, when they were sitting 9-0, the Chiefs gave up at least 287 yards passing in every game. That included 395 yards to the Chargers' Philip Rivers, 452 to the Broncos' Peyton Manning, and 346 yards to the woe-be-gone Raiders.

Then there was their playoff meltdown in Indianapolis, when Andrew Luck threw for 363 yards and rallied the Colts from a 38-10 second-half hole for a dramatic 45-44 victory.

''This is a competitive unit,'' Sutton said. ''Those guys have got to drill down.''

Notes: DL Mike Catapano (illness) missed practice for the second straight day. ... WRs Mark Harrison and A.J. Jenkins missed time with hamstring injuries. ... Former Packers general manager Ron Wolfe, a mentor to current Chiefs GM John Dorsey, was a guest at practice Thursday.