It is unclear how many have died because of the contaminated water.
Osman Mohamed, deputy commissioner of Yasdiq district, told CNN that at least 50 people had died from the poisoned water and more than 150 hospitalized.
The Mogadishu mayor's spokesman, Ali Seeko, however, reported a lower number of dead. According to an interview with Bloomberg, he said that at least 10 had died and another 80 were treated at a hospital.
The condition of those sickened by the contaminated water was not clear.
"We have taken samples of water from the well, where most of the residents got sick after using the water, and once it is confirmed that the water is contaminated then stern measures will be taken against the owner of the well," Seeko said.
The officials did not name the person or entity that owns the well.
Many wells in Somalia are privately owned due to political instability but access to safe drinking water remains a problem, in part because there is little regulatory oversight.
According to the Human Relief Foundation, "Over 1 million people [in Somalia] do not have adequate access to safe drinking water for themselves and their livestock," which exposes them to water-borne disease.
According to a United Nations report, "115 people in Africa die every hour from disease linked to poor sanitation, poor hygiene and contaminated water."