A roadside blast hit a vehicle carrying two Canadian Embassy workers in the Afghan capital of Kabul on Monday, Canadian officials said. The two were unhurt.

The embassy employees were taken to medical facilities at the Canadian base in Kabul -- Camp Julien -- to be checked.

"The two individuals very fortunately suffered no physical injuries,'' Julia Gualtieri, a spokesperson for Foreign Affairs Canada in Ottawa, told The Canadian Press.

Gualtieri did not identify the two. She said one was a Canadian Forces military police officer, and the other was a "locally engaged" embassy employee.

Canadian officials and personnel from the International Security Assistance Force, or ISAF, are investigating the incident. They are trying to find out whether the vehicle was targeted.

Witnesses said three Afghan civilians in another vehicle were seriously hurt.

The blast occurred at about 1:20 p.m. local time, and was detonated just as the vehicle was passing. The explosion left a 1.5-metre-deep crater in the busy Kabul road.

No one has claimed responsibility for the attack.

The blast occurred on Jalalabad Road in eastern Kabul. Several NATO and U.S. military bases are located along the busy thoroughfare.

Bombings on the road are not uncommon. A British soldier was killed there in a suicide attack in January last year.

Soldiers have also had to deal with land mines and shooting attacks, and U.S. commanders have warned that Taliban insurgents may step up attacks now that Afghan's harsh winter is ending.

Last week, a Canadian vehicle was shot at while returning from a patrol in the Afghan capital. No one was injured in that incident.

And over the weekend, four U.S. soldiers died when their vehicle struck a land mine in central Afghanistan. It is not clear if the land mine had been placed there recently, or was leftover from decades of civil war in the country.

There are about 900 Canadian Forces members deployed at Task Force Kabul, or Camp Julien, as part of the ISAF force in Afghanistan.

With files from The Associated Press and The Canadian Press