Residents of Sultanpuri area in the national capital, Giani, Wasim, Ayub, Wajid and Murli were killed in the mishap, police said.
"Gyani, Wasim and Ayub died on the spot while Wajid and Murali were declared brought dead at the PGI Hospital in Rohtak.
"The condition of six injured, admitted to PGI hospital, remains critical," they said.
Three buffaloes, being carried in the other truck, were also killed in the accident, according to police.
A case has been registered and investigations are on, police said.