Detectives from the Anti-terrorism Police Unit (ATPU) on Wednesday morning arrested NTSA employees after a morning raid.
The detectives raided the National Transport and Safety Authority (NTSA) main offices in Upper hill in the ongoing probe into the registration of a vehicle used by 14 Riverside terrorists.
The detectives reportedly stormed the premises at 9AM and arrested a few of the employees and took them to their Upper Hill offices for questioning.
Members of the public seeking services from the premises were also blocked from accessing the building and told to come on a different day.
After the terrorist attack that killed 21 people and injured many, police impounded a car used by the attackers but it later emerged there was another car with a similar registration number KCN 340E
There has been no official statement from the police or NTSA over the raid.