Which gas is produced by burning gas heater in winter, which causes death if accumulates in high amounts?

Which gas is produced by burning gas heater in winter, which causes death if accumulates in high amounts?

موسم سرما میں گیس ہیٹر کو جلانے سے کون سا گیس تیار کیا جاتا ہے ، جو موت کا سبب بنتا ہے اگر زیادہ مقدار میں جمع ہوجاتا ہے؟
Explanation

Carbon monoxide (CO) is a colorless, odorless gas produced by incomplete combustion in gas heaters.

It is highly toxic.

It can cause death when inhaled in large amounts.