SEATTLE – Two unarmed Terminal 18 security guards and two mechanics rounded up 22 Chinese stowaways, then called for help, those involved say.

Port of Seattle police arrived about 45 minutes after the first stowaways were spotted early Wednesday, with federal authorities arriving about 10 minutes later.

Guards Leanne Middleton and Marlena Fisher spent 35 minutes gathering the immigrants before calling Port of Seattle police at 1:35 a.m. Wednesday. They collected 18 of the 22 with help from graveyard-shift diesel mechanics Tom Hoffman and Clay Procter.

“It was one of the bravest and dumbest stunts I’ve seen in my career,” said Erik White, corporate operations manager for Reliant Security, which patrols Terminals 18 and 25. “Their sheer act of bravery overrules the part of it which wasn’t so bright: taking on … unknown alien suspects without assistance.”

The 18 men and four women spent 15 days in a 40-foot container on China Shipping Line’s MV Rotterdam from Shanghai. They’re now in federal custody at the Northwest Detention Center in Tacoma.

“Our goal is to determine if we can potentially bring charges against individuals in this country or those overseas who may have been involved” in getting them here, said Virginia Kice, a spokeswoman for the Department of Homeland Security’s Immigration and Customs Enforcement in California.

Around 1 a.m. Wednesday, Middleton saw three people standing among cargo containers at Terminal 18. They scattered as she approached but stopped when she ordered them to halt.

The stowaways were initially mistaken for members of a foreign ship’s crew. Often when a ship arrives at port, crew members wander around the terminal, Middleton said. They’re supposed to be driven from their ships to the gate.

Middleton drove the Chinese nationals to two different vessels at Terminal 18, which is operated by Seattle-based SSA Marine.

When no one recognized the group, she and Fisher called U.S. Customs and Border Protection at 1:10 a.m. Police weren’t called right away because the stowaways were unarmed, Middleton said.

But then Procter, an SSA Marine mechanic, spotted another group heading for a barbed-wire-topped fence near the terminal’s main entrance, and six to eight people hiding among the containers.

After telling Fisher to call police, he and Middleton gathered up the stowaways. A few tried to flee or hide, but most were compliant, he said.

When port police arrived at 1:44 a.m., all the stowaways had been apprehended.

Federal authorities – the Coast Guard, Customs and Border Patrol officers and U.S. Immigration and Customs Enforcement agents – arrived around 10 minutes later.

If it were to happen again, Middleton said she’d handle the situation the same way.

“We’re really not protecting any real dangerous area,” she said. “Day to day, we interact with truckers and vessels, that is why this was out of the ordinary.”