The Obama administration issued a new official terrorism bulletin on Wednesday warning about attacks from “homegrown” radicals like the one who killed 49 people in an Orlando, Fla., gay nightclub this weekend.

“In this environment, we are particularly concerned about homegrown violent extremists who could strike with little or no notice,” the Department of Homeland Security (DHS) said in the new bulletin. “The tragic events of Orlando several days ago reinforce this.”

“Accordingly, increased public vigilance and awareness continue to be of utmost importance,” it added.

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The notice is the second of its kind issued under a new federal terrorism notification system, which went into place late last year. The system is a successor to the widely mocked color-coded alert scheme used during the George W. Bush administration, and a subsequent system that was never used. The first bulletin was issued when the system was implemented on the heels of deadly attacks in Paris and San Bernardino, Calif.

A bulletin is the lowest in the three-tier system of notices about terror threats, describing current trends and concerns.

The new notice on Wednesday maintained that the DHS does not have any "specific and credible” intelligence pointing to a terrorist attack inside the U.S.

But, as this weekend’s gruesome massacre in Orlando makes clear, “the reality is terrorist-inspired individuals have conducted, or attempted to conduct, attacks in the United States,” it warned.

“DHS is especially concerned that terrorist-inspired individuals and homegrown violent extremists may be encouraged or inspired to target public events or places,” it added, noting that extremists have a propensity to “consider a diverse and wide selection of targets for attacks.”

Omar Mateen, the 29-year-old who killed 49 people before being gunned down this weekend, is believed to have been a consumer of radical propaganda material on the internet, where the Islamic State in Iraq and Syria (ISIS) has thrived. Officials maintain that the attack, which was the deadliest mass shooting in U.S. history, was not directed by ISIS or a similar extremist group and that he is not part of a larger network.

On Wednesday afternoon, the FBI described the attack as both an act of terrorism and a hate crime