At least 20 people were killed and 55 injured in a suicide car bomb attack on a bank branch in the southern Afghan province of Helmand on Thursday, officials said.A spokesperson of Helmand province's Governor told Efe news that the suspected insurgent attack on a Bank of Kabul branch in provincial capital Lashkargah took place around midday. Several civilians and security personnel were waiting to enter the building to receive their wages when the attack happened, reports said.The injured were shifted to a hospital. The number of casualties was likely to rise, said the spokesman.