"I got it on my pants," said Ashcon Sardashti, 14, pointing to a dark stain between the knee and cuff of his jeans.
Ashcon and two other students - Ben Petron, 13, and Chris Spitalere, 14 - said the fluid started oozing over the seat on which they were sitting. Ben said they thought it was an oil leak, and they told the bus driver immediately.
The driver pulled the bus to the side of Lowell Road and the students got off and waited in a neighbor's yard, not far from Golden Brook School. No one was injured, and a replacement bus arrived about 2:45 p.m. to take the students home.
"The bus driver did the right thing," School Board Chairman Al Letizio Jr. said.
Otherwise, the bus would probably have overheated, he said.
Letizio called school officials to ascertain the facts about the incident. He then described the problem as a "minor issue with the bus coolant" and said it was not a safety concern. Either a hose or a radiator had sprung a leak, he said.
"Stuff sprays out, and it's not uncommon in very cold weather for cooling and heating systems in vehicles to have problems," he said.
Letizio said school officials did not realize anyone's property or clothing had been damaged. If that was the case, the students or parents should notify the school principal, he said.