The accident occurred near the Sukhdev Vihar bus stop at around 5.15 am when the trolley truck, used to transport cars, hit a scooty.
One of the two persons on the scooty, Sushil Kumar (24), died on the spot while the other, Vikash (17), is currently admitted to the AIIMS Trauma Centre where his condition is stated to be critical, said a senior police officer.
One of the riders was wearing a helmet as broken pieces of it were found from the spot, police said.
Police are trying to get CCTV footage from the area to ascertain the exact sequence of events.
They will also be questioning the company that had employed the accused driver.