The late night sounding of emergency warning sirens in the city of Dallas, Texas, was due to a hacker being able to access and repeatedly activate the system, Dallas city officials say.
On Sunday Syed said in an email that engineers have been running silent test on the emergency warning system over the past 24 hours. The city expects to resume regular monthly testing in May.
Outdoor warning sirens sounded in Dallas overnight Friday, causing alarm despite no severe weather or other active emergency in the area.
The sirens were first heard at about 11:45 p.m., and sounded on and off intermittently across the city.
"All 156 sirens in the city were activated last night," Dallas public information officer Sana Syed said. "It does appear at this time that it was a hack. We do believe that it was from the Dallas area."
Someone was able to gain access to the system and activate the sirens, city officials said.
“I was concerned because it was dark, and we didn’t know if it was something we were driving into or walking into,” Dart bus driver Billy Summers said. He was driving his route 466 through Oak Cliff and south Dallas when the sirens began to sound.
“Most of the people on the bus were concerned about what it was. I was too. I knew the weather wasn’t bad, and it couldn’t have been a test because it was going on for so long. I told my passengers not to panic,” Summers said.
Within the first 15 minutes of the sirens going off, emergency dispatchers received around 800 calls, and the longest wait time was six minutes, according to the city’s public information officer.
"From 11:30 [p.m.] to 3 a.m. we had around 4,400 calls come into the 911 call center. Just to give you a frame of reference, from 11 p.m. to 7 a.m. we normally get about half of that,” Syed said.
The system was finally shut down around 1:20 a.m.
"First, we apologize to all of the citizens," Director of the City of Dallas Office of Emergency Management Rocky Vaz said. "We did our very best. We shut down the system as quickly as possible, and now we have pinpointed one area where they were able to get into our system and activate the sirens."
Officials originally said they expected to have the emergency sirens operational by Sunday or Monday. A tweet from Syed's official public Twitter account late Saturday said that the "outdoor warning system is now operational" and that "[m]ore safeguards [were] being put in place" this weekend. Her tweet indicated that more information would be available Sunday.