Boulder, Colo. ? At least seven of nine University of Colorado underage coeds who were hospitalized this weekend after a night of heavy drinking attended parties held at two fraternities, a year after a fraternity pledge died from alcohol poisoning, police said Monday.

Police issued nuisance party citations to the Sigma Pi and Phi Kappa Tau fraternities for the parties late Friday and early Saturday morning, Boulder police spokeswoman Julie Brooks said.

“To have this many hospitalizations for alcohol on any given night is unusual,” Brooks said. “It’s too early to talk charges (but) it’s unusual enough that we need to take a stronger look at it.”

After-hours phone messages left at the fraternities’ international headquarters were not immediately returned. Adrian Fryxell, 20, president of Phi Kappa Tau, did not immediately answer an e-mail sent by The Associated Press.

Police responded to the first call of a sick woman at a sorority house at about 1 a.m. Saturday. Another call came in from the same sorority house a short time later of a woman passed out in a hallway.

“We figured there were other girls transported (to hospitals) by other means,” Brooks said. Police checked the hospitals and found three other women who were hospitalized after heavy drinking.

Two additional sorority members – one found at her apartment and another who was transported to the hospital – were also found by Boulder police.

Campus police were also investigating two additional cases, bringing the total to nine.

Brooks said eight of the nine were either 18 or 19 years old. Their blood-alcohol level was not released but Brooks said officers, who have the discretion to take intoxicated people to a detox center or place them in the custody of sober people, felt the women needed to be hospitalized.

It was also unclear how much the women drank or where they got the alcohol. One woman told police she only remembered having one drink.

Last September, Lynn Gordon “Gordie” Bailey Jr. was found dead inside the off-campus Chi Psi house in Boulder after a night of heavy drinking.