“Four people — one Pakistani and four Ethiopians — have died… Of those who sustained injuries, four are Pakistani and four are Ethiopians,” spokesman Shimeles Kemal told AFP.
The attack took place late Saturday about five kilometers (three miles) from the headquarters of Saudi Star, an agriculture company owned by Ethiopian billionaire Mohammed al-Amoudi.
Shimeles said 10 suspects had been taken into custody and were being investigated by police. He could not say whether the suspects belong to a rebel group or were acting alone.
“The matter is under investigation, we cannot say whether this was done by individuals or politically motivated, this will be discovered by the investigation,” he said.
He said no additional security had been taken in Gambella, adding that the “regional police force has assured the police that peace and security will prevail”.
Shimeles also said the incident would not affect Saudi Star’s business activities in the country.
“There is no reason that they will interrupt their activities,” he said.
Saudi Star leases 10,000 hectares (24,710 acres) of land in Gambella, which it uses to grow rice.
Amoudi is one of Ethiopia’s wealthiest businessmen with investments in a wide array of enterprises, including a cement factory and luxury hotels.
Shimeles said the “heinous crime” would not affect the country’s development efforts, and said the act was an isolated incident.
The attack was the second by gunmen in the region in recent weeks. In March, gunmen attacked a public bus leaving 19 people dead and eight injured. The government said “anti-peace” elements were responsible for the killings.
Ethiopia’s Gambella region, which lies some 700 kilometres (430 miles) to the west of the capital Addis Ababa, is one of the most fertile and resource-rich areas of the country.
In January US-based Human Rights Watch accused Addis Ababa of forcing thousands of villagers from their land to make way for commercial farming developments, leaving people impoverished and hungry.
At least 3.6 million hectares (8.8 million acres) — an area larger than the Netherlands — has been leased to foreign and state-owned firms since 2008, with state security using force to drive people from their land, HRW said.