Two DNA polymerase molecules work simultaneously at the DNA fork, one on the leading strand and the other on the lagging strand. Each Okazaki fragment is synthesised by DNA polymerase on the lagging strand in the $5'\rightarrow3'$ direction. New Okazaki fragments appear as the replication fork opens further. As the first Okazaki fragment appears away from the replication fork, the direction of elongation is away from the replication fork.