Four-time major champion Brooks Koepka and Webb Simpson, winner of last week’s RBC Heritage tournament, are among four players to withdraw from the Travelers Championship in Cromwell, Conn., because of concerns over the coronavirus, the PGA Tour announced Wednesday.

None of the four players, who included 2010 U.S. Open champion Graeme McDowell and Chase Koepka, Brooks’ brother, tested positive for the virus. But two caddies – Ricky Elliott, who works for Brooks Koepka, and Ken Comboy, who is on McDowell’s bag – did test positive.

A Tour statement said the four players all withdrew “out of an abundance of caution.”

A fifth player, third-year Tour member Cameron Champ, withdrew Tuesday after testing positive for COVID-19.

The Tour said it has conducted 2,757 tests at tournament sites over the past three weeks with seven coming back positive. Champ and Nick Watney, who withdrew after the first round of last week’s tournament, are the only players to have been identified by the Tour as testing positive.

“While we have been thorough in building and implementing a program that mitigates as much risk as possible, we knew it would be impossible to eliminate all risks, as evidenced by the three positive tests this week,” the statement said.

The Koepka brothers, Elliott and McDowell were together Tuesday at TPC River Highlands for a practice round along with Tour player Shane Lowry. Brooks Koepka and Elliott took their second COVID-19 tests of the week after the round, and Elliott tested positive.

“I don’t want to do anything that might jeopardize the health of any player in the field or his ability to compete,” Koepka, the winner of two U.S. Opens and two PGA Championships, said in the Tour statement. “The right thing to do right now is to get home, support Ricky and feel confident that I’m doing what I can do protecting my fellow Tour members, my Tour friends and everyone associated with the Travelers Championship.”

McDowell tested negative twice, Monday and Wednesday, but Comboy had not made the trip to Connecticut after experiencing symptoms. McDowell said he had experienced some fatigue and muscle soreness in recent days but didn’t initially consider his condition to be related to the coronavirus.

“But now that Kenny has tested positive – and we’ve spent a lot of time together the past 10 days – I have to take these symptoms more seriously,” he said. “I want to do the responsible thing.”

Simpson said Wednesday he had a family member test positive for COVID-19 in the last 24 hours. His on-site test this week came up negative, he said.

“I feel like it is my responsibility to take care of my family and protect my peers in the field by withdrawing from the Travelers Championship,” he said. “I am going to return home to Charlotte and quarantine under CDC guidelines, and I look forward to returning to competition after that time period.”