Lahore, Pakistan (CCTV/CNN) - Suspicious deaths of more than a dozen people on cough syrup medication in Pakistan have been reported as investigations continue to determine the cause.
Since Nov. 23, a total of 18 people died as a result of blood clotting in the heart, according to an initial post-mortem report released Wednesday.
The cause of the blood clotting, however, remains unknown.
According to reports, more than 20 people in total are thought to have consumed the medication syrup, with a large proportion confirmed dead. The rest are said to be in hospital seeking emergency treatment, few in serious condition and some even have been released from hospital.
The syrup is reported to have shown no health and safety concerns, according to Tuesday's preliminary investigation, as it further highlighted that excessive use of the medicine or mixing it with other medicines could have caused the fatalities.
The 18 deaths were confirmed as of Thursday after they drank "Tyno" branded cough syrup in Pakistan's eastern city of Lahore.
Police authorities have since sealed the factory producing the syrup, as it arrested the owners of the three drug stores selling the medicine as part of its investigation.
The case is still under the investigation.