Rooms of the athletes and physical trainer Christopher Xuereb of Canada were searched and drugs and muscle supplements were seized, Udine police captain Antonio Pisapia told The Associated Press.
Pisapia said it was unclear if the drugs and muscle supplements were legal or illicit and that the substances were being analyzed.
"We are examining the substances now," Pisapia said. "No arrests have been made and nobody has been placed under investigation."
Meanwhile, discus thrower Allison Randall acknowledged that she was one of the five Jamaican athletes who tested positive for the stimulant oxilofrine at the Jamaican championships last month, along with Powell, a former world-record holder at 100 metres, and Simpson.
Randall holds the island's record for the discus throw and competed at the London Olympics. Her statement says she was "shocked and surprised" at the findings and hopes her backup sample will clear her name.
The Jamaica Athletics Administrative Association issued a brief statement Monday saying an anti-doping management process has started for the athletes. It did not identify the two other athletes who tested positive.
Both Powell and Simpson train under Stephen Francis, a coach at the high-profile MVP Track and Field Club in Jamaica. In an interview on Jamaican radio station HITZ 92 on Monday, Francis blamed the positive tests on Xuereb.
"We are not disowning Asafa, we are just saying this relates to his personal employee. The trainer has nothing to do with MVP," Francis said.
Francis told the radio station that he told Powell to only trust people who were with him from the start.
"If you are going to sink, sink with people who were always around," he said.
Xuereb didn't immediately return an email seeking comment from The Canadian Press.
According to his Linked In profile, Xuereb is from Toronto and "coaches elite and Olympic athletes (past and present) from Canada, U.S.A. and the Caribbean."
The profile says that Xuereb specializes in track and field and soccer and is also a speed/power coach, soft tissue massage and treatment specialist and health and nutritional adviser.
Under accomplishments, he lists 2009 World Track and Field and the "2012 Olympics (part of winning gold and silver medals)."
The raid at the Fra i Pini hotel in Lignano Sabbiadoro in northeastern Italy came in stark contrast to the usual warm reception that the runners generally receive in Lignano, and the town's mayor, Luca Fanotto, recommended "caution" before drawing conclusions.
"The Jamaican team has chosen the sports facilities of Lignano Sabbiadoro as their training base for years and they never forget to thank the city from podiums all over the world," Fanotto said in a statement.
A local athletics meet is scheduled for Tuesday in Lignano and the Jamaicans had been scheduled to compete as they do most years. However, neither Powell nor Simpson were on start lists released Monday.
The police captain with the specialized NAS unit added that Powell and Simpson were informed of the positive tests Saturday morning.
The news of the positive tests for Powell and Simpson came the same day that American 100-meter record holder Tyson Gay revealed that he also failed a doping test.
Powell was the last man to hold the 100-meter world record before Usain Bolt broke it in 2008. He also helped the Jamaicans to the 4x100-meter relay gold medal at the 2008 Olympics.
Simpson won Olympic gold in the women's 4x100 relay in 2004 and silver in 2012, along with an individual silver in the 100 in 2008.
The doping positives come a month after another Jamaican Olympic champion, Veronica Campbell-Brown, tested positive for a banned diuretic.
Associated Press Writer David McFadden in Kingston, Jamaica, contributed to this report.
— With files from The Canadian Press