The patients died in the clinic in Putumattalan on Monday, Red Cross officials said on Tuesday, Feb 10.
The ICRC did not say who fired the latest shells in an area where both the army and rebel Liberation Tigers of Tamil Eelam (LTTE) are active.
"Once more, we call on both parties to meet their obligation under international humanitarian law to spare at all times the wounded and sick people, medical personnel and medical facilities," the ICRC said.
"We are shocked that patients are not afforded the protection they are entitled to," Sophie Romanens, from the ICRC, told Al Jazeera, adding that the agency was able to evacuate some citizens from the area by sea.
"Our concern now is to be able to continue with the medical evacuation ... there are no medical facilities [in the region]," Romanens said.
OneIndia News (With inputs from Agencies)