LOS ANGELES - Popular police drama CSI: Crime Scene Investigation became the second long-running television series in a week to get the axe, following American Idol's cancellation on Monday.

CSI, which ends its 15-year run with a two-hour finale on Sept 27, was once the most-watched show in the world on TV network CBS and enjoyed several spin-offs. At its peak, it attracted 26 million viewers in the United States and 63 million worldwide.

But with a tired formula that critics say have grown boring, the ailing show's viewership averaged 11.2 million on its latest season.

While some fans claimed that it was inevitable following the series' decline in quality, many were nostalgic and mourned its demise.

Adelene Lim posted on The Straits Times' Facebook page: "Sad to see it go. But saw this end coming."

"After the original cast members departed one by one, it signalled the downfall of the series. It was difficult to relate to the newer ones - lack of on screen camaraderie," said Evan Chong.

Here's how fans online have been reacting to the news: