Confirming the injuries, County Police Commander Richard Kerina who was among the top security officers who visited the scene said a swift response by the police helped in saving lives.
According to witnesses, hooded militants armed with AK-47 rifles kidnapped a man from a nearby village and ordered him at gunpoint to take them to the Chinese construction site.
As they approached the camp, they started shooting indiscriminately prompting the workers who are housed outside the fenced camp to scamper for safety.
Kerina said security officers guarding the camp returned fire, and in about 15 minutes were able to repulse the militants who fled to a nearby thicket.
The police officer said the police are pursuing the militants, who were said to have escaped on foot towards the Dadaab area, 100 kilometers from Somalia.
Northern Kenya has experienced similar attacks from the militants, who cross over to Kenya from neighbouring Somalia.
Meanwhile, three suspected Al-Shabaab militants armed with Ak-47 rifles and several rounds of ammunition, who were arrested in Hagaderas refugee camp in Dadaab over the weekend, have been transferred to Nairobi for further interrogation.
The attack by the militants comes barely a week after four al-Shabaab militants launched an audacious attack last Tuesday, killing 21 people in an upmarket complex in Nairobi.