The federal agency that investigates major crashes is criticizing the federal agency that oversees truck and bus safety.

In a press release, National Transportation Safety Board officials said a bus explosion and fire that killed 23 nursing home patients who were fleeing Hurricane Rita was partly due to lax oversight of bus companies by the Federal Motor Carrier Safety Administration.

The NTSB found that a lack of lubrication in a wheel assembly probably caused the fire.

However, NTSB officials said FMCSA was also partially responsible because it had done a poor job of making sure that bus companies are safe.

In January, Global Limo owner James Maples received probation for his company's involvement in the incident, down from a potential sentence of up to two years in jail.

Maples was convicted of poorly managing his fleet, but was acquitted on the more serious charge of falsifying driver's logbooks.