Fans will pass through walk-through magnetometers while their tickets are being scanned. Devices are being installed at all public entrances to the park. Those who do not wish to pass through a metal detector will have the option of being checked with a hand-held device.
The increased security measures are the result of MLB's continuing work with the Department of Homeland Security to elevate and standardize security practices across the game. The added security measures are in addition to bag checks that are conducted at all MLB ballparks.
"Fan safety and security is our top priority," said Sylvester Servance, the Mariners director of security, in a news release. "The Mariners and Major League Baseball are keenly aware of the current security environment at public events. We believe this step is necessary, poses minimal inconvenience, and ultimately will serve the best interests of all fans."
Metal detectors will be installed at Safeco Field's left-field gate this week and will be operational for FanFest on Saturday and Sunday.
"We think it's important to get started now with staff training and to familiarize the public with what they can expect this season," Servance said. "We don't think there will be any major problems moving fans through the gates."
The Mariners will continue to enforce the longstanding policy that allows bags, backpacks and purses as long as they are not larger than 16 inches by 16 inches by eight inches. All bags, including women's purses, will continue to be subject to inspection at ballpark gates.
Greg Johns is a reporter for MLB.com. Follow him on Twitter @GregJohnsMLB as well as his Mariners Musings blog. This story was not subject to the approval of Major League Baseball or its clubs.