On the penultimate day of operations at Island Air, most passengers arrived to board flights having no idea that their return flights with the airline now ceased to exist.

“Holy smokes,” said Tim Jerry, of Minneapolis, shortly after entering the terminal Thursday afternoon and joining the line with his wife, Kathy, for a flight to Kona to celebrate their 30th wedding anniversary.

“We didn’t have a clue,” Kathy said.

Island Air’s terminal desk agents soldiered on Thursday checking in passengers, arranging alternative flights and bearing up under customer frustration despite knowing they’ll be among the carrier’s 423 employees losing their jobs.

Things grew tense at one point when a middle-aged woman, who declined to give her name because she’s a member of the military, asked for an Island Air manager to help her party arrange alternate flights and get a refund but was told no managers were available. Her group of four had booked at least $1,000 in airfare to Kona and Kauai on the airline, she said.

She turned to the dozen or so passengers waiting in line behind her and informed them that the carrier was going out of business. An airport security officer briefly approached her to make sure the situation did not escalate.

“How are we getting home?” Kapolei resident Lorraine Gershun said aloud Thursday, reacting to the news as she and her husband, David Weisberg and their daughter, Jaymee Weisberg, arrived for a flight to Kauai. The family was taking a long weekend on the Garden Island.

“We kind of knew they were not (in good shape),” Gershun said. Still, the family didn’t expect to have their return flight canceled. After leaving the desk, they said they booked a flight on Hawaiian Airlines and intended to pursue a refund with Island Air later.

“People are really gracious,” Honolulu resident Morgan McKeown said of the Island Air desk agents after he re-booked a Kauai trip with his family, including his parents who are visiting the islands, on Hawaiian.

McKeown described the agents as “calm under pressure” — but also visibly sad about the looming closure.

“Our hearts go out to the employees who deserve a huge mahalo for decades of service to our community,” said Linda Chu Takayama, director of the state Department of Labor and Industrial Relations, which will send a rapid-response team today to the Island Air terminal to help employees.