On Friday, New York City's medical examiner revealed that the death of "The Wire" and "Boardwalk Empire" actor Michael K. Williams was caused by an accidental drug overdose involving fentanyl.

According to the New York Times, the medical examiner said the official cause of death was "acute intoxication by the combined effects of fentanyl, p-fluorofentanyl, heroin and cocaine."

Williams, 54, was found deceased in his Brooklyn apartment on Sept. 6.

Although a number of drugs were discovered in his system at the time of his death, that does not necessarily indicate that the drugs were taken at the same time, or whether he had knowingly ingested or used them.

According to the New York Times, fentanyl is a synthetic opioid that can be an upwards of 50 times more powerful than heroin and is cheaper to distribute and produce.

The powerful opioid "has seen increased use in the United States in recent years as an alternative to heroin or prescription opioids. It has also contributed to a rise in fatal overdoses among older people and African-Americans," wrote the New York Times.

Most commonly, fentanyl is mixed with heroin, although the mixture of cocaine and fentanyl recently received attention after eight people on Long Island overdosed after taking the combination. Six of those overdoses reportedly proved fatal.

Williams reportedly started taking drugs during the filming of "The Wire," a show in which he played Omar Little, a thief who robbed drug dealers.

According to the New York Times, there has been a surge in overdose deaths across the US during the pandemic. New York City alone saw a record-breaking rise in these deaths, with more than 1,600 people dying during the year and about five dying every day. A majority of those deaths involved fentanyl.