OTTAWA -- Global Affairs Canada says it's aware of reports that two Canadian citizens have been kidnapped in Nigeria.

Spokesman John Babcock says consular officials in Nigeria are in contact with local authorities to gather additional information.

Babcock says further details can't be released for privacy reasons.

A state police spokesman says gunmen ambushed two Canadians and two Americans travelling through Nigeria's northern Kaduna state, kidnapping them and killing two policemen.

Kaduna state police spokesman Mukhtar Aliyu said Wednesday that the foreigners were heading south from Kafanchan in Kaduna state to the capital, Abuja, on Tuesday night when they were ambushed around Kagarko.

Aliyu reported earlier in the day that only two people were kidnapped, one American and one Canadian, but revised the numbers based on updated information.

"The two police escorts attached to them engaged the kidnappers in a fierce gun battle, which resulted in the unfortunate death of the two police officers," he said.

The kidnapped foreigners are investors who were setting up solar stations in villages around Kafanchan, according to Aliyu.

Security officers, including an anti-kidnapping unit, have been sent to the area to try to rescue the North Americans and to apprehend their abductors, he said.

Kidnappings for ransom are common in Nigeria, especially on the Kaduna to Abuja highway. Two German archaeologists were seized at gunpoint last year less than 100 kilometres northeast of Abuja and later freed unharmed. Sierra Leone's deputy high commissioner was taken at gunpoint on the highway in 2016 and held for five days before he was let go.

Victims typically are released unharmed after ransom is paid, though security forces have rescued a few high-profile abductees.

A number of bandits, including herdsmen, have been arrested.

Global Affairs advises against non-essential travel to Nigeria and says Kaduna should be avoided "due to the high risk of terrorism, inter-communal violence and kidnapping."

-- With files from The Associated Press.