Detroit water officials are investigating the cause of a 48-in. concrete water main that burst in Livonia, Mich., around noon July 12, sending a four-foot-high geyser into the air and flooding Interstate 96.

The rushing water washed away part of an embankment against the freeway, clogging catch basins and sending drivers climbing onto the roofs of their cars for refuge.

A Livonia city official was caught in the flood early on. "It was shooting up a good four feet," says Brian Williams, assistant superintendent. "Fortunately, my city-issued Malibu Chevy made it through."

The same high-pressure water main broke about a mile away four years ago, notes Williams. Crews took "some weeks" to repair the transmission line," he says.

Details on the condition and age of the water main prior to the break are not yet available. Williams estimates that it was built in the early 1970s, along with the highway.

Crews working for the Detroit Water and Sewerage Dept., which owns and operates the line, say they are investigating the cause of the break.