Omar Zwak, spokesman for the governor of restive Helmand province confirms the incident.
He said that the ones killed included five civilians and two soldiers.
Pacha Gul Bakhtyar, security officer of the police headquarters of Helmand province also confirms the suicide attack in Sangin District.
He said that a suicide bomber exploded his explosive laden truck close to a security center around 02:00 PM this afternoon.
He told Khaama Press that both the ones killed and injured included security personnel and civilians.
There is no immediate claim of responsibility for the attack but Taliban insurgents have carried out these types of attacks in the past.
Helmand is one of the volatile provinces in the southern part of Afghanistan. Due to the increase in insecurity, Afghan National Security Forces (ANSF) have begun a big scale of military operations in the target areas of this province.
The military operation kicked off from Sangin District about 11 days before but has extended to other neighboring Districts of Sangin.
Hundreds of soldiers are taking part in this operation and at least 100 insurgents have been killed in the operation Zulfiqar so far.