Updated

The parents of four college students missing in Haiti called on the U.S. government to step up its rescue operations in the earthquake-ravaged country Monday, saying the failure to locate their children after nearly a week was "inconceivable."

"We're hoping today for a miracle," said Jean Gianacaci, whose daughter Christine is one of four Lynn University students still missing in the wake of the 7.0-magnitude quake that rocked the impoverished island nation on Tuesday.

"These kids were not on spring break," said Giannacaci — her voice breaking. "These kids were down with the poorest of poor, helping."

Four students and two faculty members from the South Florida college remain unaccounted for. They were among a group of 12 traveling with the charity Food For The Poor when the hotel at which they were staying in Port-au-Prince collapsed during the quake.

The university had previously announced that 11 of the 12 were safe and accounted for, but later retracted the report, saying it was based on "bad intelligence."

"It just seems inconceivable to me that we can't get the manpower there to make this happen," said Lin Crispinelli of Katonah, N.Y., whose daughter Stephanie is missing. "It's devastating. They're living a hell and so are we."

In a direct appeal to President Obama, Leonard Gengel of Rutland, Mass., said, "We want your help."

The missing students and faculty are: Stephanie Crispinelli of Katonah, N.Y.; Courtney Hayes of Boca Raton, Fla.; Britney Gengel of Rutland, Mass.; Christine Gianacaci, of Hopewell, N.J.; and Professors Patrick Hartwick and Richard Bruno.

The eight Lynn University students located in Haiti were evacuated to the Dominican Republican immediately after the earthquake and returned home to Fort Lauderdale early Friday.