AVA- "The incident occurred early morning in Hajji Shirin area of Nad Ali district. The blast also damaged parts of the military camp," the official who declined to be named told media.
The Afghan security forces have cordoned off the area for precautionary measures.
Further details about the incident are still forthcoming amid the absence of any official statement.
The Taliban militant group has claimed responsibility for the attack.
Zabiullah Mujahid, a purported Taliban spokesman, tweeted that a Taliban fighter launched a truck bombing against a joint Afghan security forces' compound in Nad Ali, leaving huge casualties among the Afghan army and police forces.
Helmand, notorious for poppy growing, is also a known Taliban stronghold.
The Afghan security forces have seen rising casualties since the beginning of 2015 when Afghan soldiers and police assumed full responsibilities of security from the U.S. and NATO troops.