Low-cost inter-city buses are one of the fastest-growing forms of transportation, and have sprouted up increasingly in the D.C. area, where every day they make trips to New York and other cities. The District moved just this week to regulate where they can idle, post signs and load passengers. But after a crash in the Bronx killed 15 last weekend, U.S. officials say their operation is dangerously unsupervised.

Drivers must have a commercial license and are supposed to drive no more than 10 hours a day.

The driver of the bus in the crash had previously served prison time for manslaughter and had also been arrested for driving on a suspended license.

According to the New York Times: “Senator Charles E. Schumer of New York called on the National Transportation Safety Board, which is investigating the crash on Saturday, to examine whether the Federal Motor Carrier Safety Administration — the agency charged with overseeing the tour-bus industry — had put in place sufficient tools to ensure passengers’ safety.”

NTSB vice chairman Christopher Hart said of the driver, according to the AP: “We want to know what he ate, what he drank and how much he slept.”