Major winners Darren Clarke, Patrick Reed and Scottie Scheffler confessed their golfing problems were put very much in perspective by this week's school shooting massacre in Texas.

Clarke opened with a three-under 68 to lie four shots off the pace alongside Pádraig Harrington in the KitchenAid Senior PGA in Michigan as reigning Masters champion Scheffler and 2018 champion Reed carded four-under 66s to share the lead with Webb Simpson, Harold Varner III, Chris Kirk, Nick Taylor, Cam Davis and Beau Hossler in the Charles Schwab Challenge where PGA Championship winner Justin Thomas shot 71.

All wore black ribbons and were deeply affected by the school shooting in Uvalde, Texas, earlier this week, where 19 children and two teachers were killed by a lone gunman.

"That's why we stopped at 12:36 today," Clarke said at Harbor Shores Resort. "It was for what happened a couple of days ago. And we rightly stopped. It was a wonderful and the right thing to do."

Texans Scheffler and Reed also expressed their sadness at the tragedy, which took place just 350 miles from this week's PGA TOUR stop.

"I can't imagine what those families are going through right now," world number one Scheffler said at Colonial. "It makes me sick to my stomach just to think about it… All we can do is just pray for them."

Reed said: "It's one of those things that definitely puts a perspective on what we do."

Clarke was tied for 17th after his five-birdie 68 as Harrington made four birdies and a bogey to match him late in the day as they trail Bob Estes and Steven Alker by four strokes.

In the Netherlands, Joost Luiten (36) shot a seven-under-par 65 to lead by a shot from England's Eddie Pepperell and Denmark's Rasmus Højgaard as he bids for his third win in the Dutch Open at Bernardus Golf.

Clandeboye's Jonathan Caldwell was 47th after a one-under 71, while Cormac Sharvin's struggles continued as he posted four birdies, five bogeys and a double-bogey in a 75.

Meanwhile, Portmarnock's Conor Purcell and Greystones' Paul Dunne opened with two-under 69s to share 15th, five shots behind England's Nathan Kimsey in the Farmfoods Scottish Challenge at Newmachar.

"I'm happy enough," Purcell said. "I played solid all day. It's a course where there are plenty of chances if you keep it in play and stay patient."

Coming off three missed cuts in a row, Dunne was pleased with his start, adding: "The wind got up quite a lot this afternoon, so it was tricky. Lots of swirling crosswinds, so I was happy to keep it steady and hang in there."

Kinsale's John Murphy had an eagle two at the 14th in a 70 to share 31st with Tom McKibbin on one-under as James Sugrue shot 74 and Gavin Moynihan a 76.