New York ( CNN ) -- Four people were killed early Saturday when a double-decker Megabus slammed into a railroad overpass and turned on its side in Salina , New York . Authorities said 25 passengers were transported to the hospital . By Saturday evening , five were still in the hospital , while one person was injured critically , said Onondaga County Sheriff Kevin Walsh . The owner of the bus said it was off its designated route , but did not explain why . `` Obviously the driver did n't see the signs or did n't realize the height of his bus , that the double-decker bus would n't fit under that bridge , '' Walsh told CNN affiliate YNN . Walsh said authorities suspect the driver missed a turn when a road split . A flashing yellow light alerts drivers of a low bridge , he added . The bus , part of a fleet of low-cost express buses , was on its way to Toronto , Canada , from Pennsylvania . The accident occurred around 2:30 a.m.on the Onondaga Lake Parkway in Salina , a Syracuse suburb . `` Our immediate thoughts and concern are with those who have lost their lives or been injured , as well as their families and loved ones , '' a Megabus spokesman said . `` Safety is our absolute priority and we will be carrying out a full investigation into the accident as well as assisting the police and other authorities in any way that we can . '' The dead were people from India , Malaysia , New York and a Midwestern state , Walsh said . Don Carmichael , senior vice president of Coach USA , which operates Megabus , said the company was tending to the needs of those on the bus . `` The key thing is to ensure that our customers and passengers are looked after , '' he told reporters . CNN 's Jackie Castillo contributed to this report .
UP : Five people are still in the hospital ; one is in critical condition . UP : Flashing yellow lights warned motorists of the bridge . The Megabus was on its way to work . It was off route , but the company did not know why .