The workers were in Rivers State, returning from an official trip to Bayelsa state, when they were attacked.
"The Shell Petroleum Development Company of Nigeria Limited (SPDC) regrets to confirm the attack on its staff and government security escort at Rumuji, Rivers State, on the East/West road on Thursday, April 25, 2019 around 16:00 hours," an SPDC spokesman said.
"We are supporting the police in their investigation of the incident. We cannot make further comments at this time."
A Rivers state police spokesman said that efforts were underway to rescue the workers.