Pokemon GO servers have had issues since the game was publicly released. While most of that is due to the game's massive popularity, some stem from more malicious intent. The hacker group OurMine recently took credit for a distributed denial of service (DDoS) attack on Niantic's server. OurMine claims to be a white hat hacking group spreading awareness about security. However, their methods have come under a great deal of scrutiny. In addition to server attacks, they've also claimed responsibility for taking control of the Twitter accounts of Twitter founder Jack Dorsey, and multiple YouTube stars including PewDiePie and Markiplier. In all those cases, OurMine typically demands the owner of the servers or accounts contact them. They claim it is to promote services to better protect their accounts. TechCrunch says however that they often charge several thousand dollars for their services. As well, their behavior utilizing the account often takes on the appearance of a group taking accounts hostage, rather than a group spreading a message about security.
Prior to the attack, OurMine announced their intentions in another blog post, stating they will be attacking the Pokemon GO login servers. They demanded that Niantic staff contact them, and encouraged readers to email the company. OurMine says this is for the protection of these servers, one member saying, "We don’t want other hackers attack their servers, so we should protect their servers". Another group called Poodle Corp (disclaimer: music plays automatically) also claimed credit for the DDoSing of Pokemon GO servers.https://twitter.com/PoodleCorp/status/754298236093857792
To find out about outages in your area, you can use DownDetector. As Pokemon GO expands to more regions, players should expect some additional downtime. Obviously with the popularity of the game, Niantic's servers are under a great deal of stress. Niantic said on the official Pokemon GO Twitter that they've removed the issue but did not state outright that the cause was a DDoS.https://twitter.com/PokemonGoApp/status/754531335969075200
Most likely the majority of server issues users will face is organic, however OurMine is notorious for this. If their intent is only to uncover and help protect from security vulnerabilities, then why not simply uncover them without actually attacking those servers, and then publicly announcing the ability to other hackers with more malicious intent?