India, May 26 -- At least six people, including a Bihar Police sub-inspector and a prisoner in police custody, were killed when a double-decker AC bus overturned on the Lucknow-Agra Expressway in Uttar Pradesh's Unnao district early Tuesday morning, police said.

The accident occurred around 5am near milestone 262 when the Delhi-to-Bihar bus reportedly went out of control and overturned along the roadside railing.

According to a preliminary police investigation, the driver is suspected to have dozed off, leading to the crash.

Eyewitnesses said the bus was moving at high speed before the driver suddenly lost control. The vehicle hit the divider and overturned, leaving several passengers trapped and some thrown out through the windows ont...