Following the unlocking of Lugia and Articuno after the disastrous "Pokemon Go Fest," two more legendary Pokemon have been announced by game developer Niantic.

In a long statement posted on the company's blog, Chief Executive Officer John Hanke announced the arrival of the next two legendary Pokemon — Moltres and Zapdos. Other than Lugia, each of the legendary Pokemon will be available for one week only.

Articuno, which was one of the two Pokemon first made available over the weekend, will be so until July 31. Moltres will released starting July 31 and available through Aug. 7. Zapdos will be unlocked next, and will be available from Aug. 7 to 14.

In his statement, Hanke also apologized for the numerous technical issues encountered by many players during the "Pokemon Go Fest" held at Chicago's Grant Park on Saturday. "Both I personally and all of Niantic apologize for the inconvenience and frustration," he said. He also gave insight as to what contributed to the problems that prevented the players to access the game.

He cited technical issues with the game software as reasons for the client crashes that occurred. They resolved the glitches by performing a server configuration change, which addressed the problem for many, but not all. For the network access problem, he said that his company provided attendance and required data throughput estimates to major cellular carriers to allow them to plan for the event. However, many attendees were still not able to play the game due to overburdened networks.

After the "Pokemon Go" event, players were able to play the game as they moved to surrounding areas of the venue, where cellular networks were not as overloaded. In the same post, the company chief shared that from late Saturday to Sunday, "Pokemon Go" players in downtown Chicago participated in more than 69,000 Raid Battles and captured more than 7.7 million Pokemon, including more than 440,000 legendary Pokemon.