The 26-year-old man was on his way to work on a two wheeler when the mishap occurred near Nelamangala here. The impact was such that his body was severed into two, they said.
A video clip of the man with severed body lying in a pool of blood calling for help was broadcast by local channels.
The man pleaded for help for some time, a person claiming to be an eyewitness, told a TV channel.
Police said the lorry driver was arrested and case booked against him under various sections of the IPC, including 279 (Rash driving or riding on a public way).