The hit game appears to have suffered two spates of outages over the weekend. A group calling itself PoodleCorp claimed responsibility for the first, on Saturday. It’s particularly hard to verify this one—not only does this group not have much of a track record, but the “attack” coincided with the release of Pokémon Go in 26 more countries.

The kind of attacks being referred to here are called distributed denial-of-service (DDoS) attacks, where the hackers commandeer networks of computers to flood the target’s servers with connection requests until they freeze up.

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The effect is pretty similar to, say, hordes of users overwhelming the servers of a game whose makers didn’t anticipate the level of demand. And we already know that the Pokémon Go craze has led to instability in the system—in fact, server capacity issues are delaying the game’s Japanese launch.

Casting doubt on the claim that attacks were responsible for Saturday’s problems, the game’s maintainers tweeted early Sunday that they had figured out the cause of the “server problems.”

The issues causing the server problems have been identified. Trainers should once again be able to search for Pokémon in the real world.

— Pokémon GO (@PokemonGoApp) July 17, 2016

However, an unofficial Pokémon Go server status site shows there were intermittent but serious outages throughout Sunday. After the announcement of Pokémon Go‘s availability in Canada on Sunday, it was reported that the game’s systems were overloaded, leaving hopeful players struggling to register an account.

And that’s where OurMine may come in. This group has more of a track record, having previously hacked the social media accounts of high-profile tech execs, and it claimed responsibility for Sunday’s Pokémon Go attack on its website.

OurMine pitches itself as an “elite hacker group” that performs vulnerability assessment for companies—that is, they figure out where the flaws in companies’ defenses lie, then recommend how to fix them. “We have no bad intentions and only care about the security and privacy of your accounts and networks,” their website reads. A spokesperson for OurMine told Fortune that the group does not request money from its targets.

Before Sunday’s “attack” began, OurMine said it would make Pokémon Go inaccessible to its users until the proprietors (former Google subsidiary Niantic Labs and the Nintendo-backed Pokémon Company) contact OurMine “to teach them how to protect it!”

OurMine’s representative said it stopped its attack against the game’s servers on Monday morning. Will the group resume the attack? “We don’t know, but I think no,” the spokesperson said.

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The representative said neither Niantic nor the Pokémon Co. had “yet” been in touch to take OurMine up on its offer of a security lesson. The rep added that it was not known whether an attack was really responsible for the earlier outages on the weekend, “but I think it wasn’t PoodleCorp, because the servers were down before their tweet.”

Fortune has asked the Pokémon Co. for its take on the weekend’s outages, but had not heard back at the time of writing.

Meanwhile, shaky servers aren’t the only security-related worry for Pokémon Go fans. It also emerged last week that a malicious app claiming to be associated with the game had made its way into the Google Play store.