History has cancelled the SEAL Team drama Six, which is in its 10-episode second season. The cancellation was reported in several outlets and confirmed on social media: History's official Twitter page for the show retweeted one such announcement by lead actor Barry Sloane.

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The season (and series) finale is slated for July 25. 

The A+E Studios produced series initially starred Walton Goggins as leader of a Navy SEALS team. The show also depicted the team members' home lives and drew plaudits from veterans' groups for its realism. The second season viewing audience, though, has been down about half from its debut season, Varietyreported.

Syfy said it had given a two-season final order for space drama Killjoys ahead of tonight's third-season finale and it also cancelled, without a press release, the space drama Dark Matter after three seasons.

Dark Matter showrunner and creator Joseph Mallozzi announced his show's cancellation in a blog post and on Twitter "with great sadness" Friday afternoon. "To say that I’m incredibly disappointed would be an understatement," Mallozzi, whose past credits include three Stargate TV series on Syfy, said on his blog, thanking fans for support and adding, "You all deserved better."

Fans of Killjoys, meanwhile, received a reprieve in the form of a 20-episode order to Temple Street, a unit of Boat Rocker Studios, and Syfy corporate sibling Universal Cable Productions. Creator Michelle Lovretta is executive producer with Karen Troubetzkoy and Temple Street’s David Fortier and Ivan Schneeberg. Season four will air in 2018. The show also airs on Space in Canada. Universal Cable Productions distributes the show worldwide except in Canada, where the series airs on Space.

“Helmed by Lovretta and driven by the superb storytelling, we are excited to bring Killjoys back for two final seasons,” Bill McGoldrick, executive VP of scripted development for NBCUniversal Cable Entertainment, said in a release. “Tonight’s game-changing season finale sets the tone for the final chapters of our bounty hunter’s space adventures and we cannot wait for our talented cast and crew to bring to life what is sure to be an epic journey that will leave our passionate fans on the edge of their seats.”

In the release, Lovretta said: "This renewal is the kind of privilege every creator hopes for – a chance to plan the end of your story with the luxury of 20-episodes to do it. I’m immensely grateful that both of our network partners -- along with Temple Street and UCP -- have given our team, cast and fans this incredible opportunity.”

Earlier, Syfy had given a third-season renewal to Wynonna Earp, the third show in a Friday-night scripted block on the NBCUniversal-owned network.

READ MORE: Syfy brings 'Wynonna Earp' back for a third season, fans learn at Comic-Con

Mallozzi, who also was executive producer (with longtime collaborator Paul Mullie) of Dark Matter, had been campaigning on social media for a fourth-season renewal, citing among other things the show's audience growth in delayed viewing over three to seven days and a popular cast. In recent weeks, he'd noted the show was Syfy's top scripted series in overnight viewing. Dark Matter's third season ended last Friday (Aug. 25).  

"I’ll save my comments and field your questions in a future blog entry," Mallozzi, whose Twitter handle is @BaronDestructo, said. "For today, I just want to extend a heartfelt thanks to my amazing crew, my wonderful cast, and to all of you, our incredible fans."

He also congratulated Killjoys and said "wish we were going with you!"

Cast members Anthony Lemke, Zoie Palmer, Jodelle Ferland and Alex Mallari Jr. also posted notes to fans.

A Syfy spokeswoman said the network would not comment officially on Dark Matter's fate.