Police said the incident occurred at around 7.45 p.m when two 'Molotov cocktail' bombs at the camp, district police chief Mariahom Kharkrang, the of , told IANS.
He said four people suspected to be involved in the incident have been picked up for interrogation.
"We are suspecting that the attacks was carried out by members of the ten social organizations ahead of Monday's dawn-to-dusk statewide shutdown demanding the implementation of the inner line permit in the state," said Kharkrang.
Chief Minister Mukul Sangma had rejected the implementation of the inner line permit, but promised to implement a strong law to check the influx of illegal immigrants.
On Saturday, the East Khasi Hills district administration has imposed prohibitory orders banning carrying of arms, weapons, sale of petrol/diesel or any other inflammable materials in loose jerrycans/jars/ bottles to any person(s) by any petrol pump or refilling station or private individuals dealing with the sale or storage of such inflammables.
The 10 social organisations sought restrictions like the inner line permit - required by Indian citizens to enter Arunachal Pradesh, Nagaland and Mizoram - saying that the influx situation in Meghalaya might go out of control given its proximity to Bangladesh and Assam.
Joe Marwein, the spokesman of the organisations, said the implementation of the ILP would help protect the tribal population from being "annihilated" in their own land.