ST. LOUIS – The National Hockey League has issued a $5,000 fine to St. Louis Blues forward David Perron for cross-checking Colorado Avalanche forward Nazem Kadri in Game 4 of the second-round playoff series.

The hit came in the second period of the Blues’ 6-3 loss to the Avalanche Monday. The Avalanche led 3-1 when Blues forward Pavel Buchnevich delivered a hit on Kadri against the boards. Shortly after, Kadri gave Perron a late shove, causing retaliation by Perron and Buchnevich that landed them both in the box with minor penalties.

Kadri scored a hat trick in Colorado’s Game 4 victory. The performance came after a first-period collision with Blues goalie Jordan Binnington in Game 3 on Saturday night.

St. Louis police and the NHL are investigating threats made towards Kadri. The NHL told the Associated Press on Monday that it is working with the St. Louis Police Department to employ enhanced security procedures both at the arena and in the hotel in response to the threats.

No other fines or suspensions have been announced in the series as of Tuesday afternoon. Colorado leads the second-round series, 3-1, pushing the Blues to the brink of elimination.