More than 70,000 customers have been impacted by outages across AT&T’s network Thursday morning, causing internet and cellular service outages, according to Downdetector. 

About 1 in 2 customers that reported issues said they had problems with their mobile phones, while another 40% said they had no signal. The most affected locations are Austin, Houston, San Antonio, Indianapolis, Chicago, Atlanta, Miami, Dallas, and New York City.

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“Some of our customers are experiencing wireless service interruptions this morning. We are working urgently to restore service to them,” said AT&T in a statement to TIME. “We encourage the use of Wi-Fi calling until service is restored.” The cellular company did not provide any details as to what is causing the outages.

Reported outages reached a peak of nearly 74,300 outages at 9:15 a.m. ET, though the number of reports are now dipping.  

Other providers such as Verizon, T-Mobile, received reports of outages on a much smaller scale, and say that their network is functioning fine.

In Chicago, where a high number of outages were reported, the city’s Office of Emergency Management & Communications said that the 911 center was still fully operational.  

Here’s what to know about the outages. 

Cricket Wireless outage reports

Cricket Wireless, which is owned by AT&T, saw a peak of 13,638 reports of outages around 7:45 a.m. ET. Now, just over 12,000 customers are reporting outages. About two-thirds of people who reported outages said they had no signal. 

Cricket told TIME that three-quarters of their network has been restored as of around noon ET. “We are working as quickly as possible to restore service to remaining customers,” they said.

Verizon customers experience issues

Verizon said that their network is working normally. “Some customers experienced issues this morning when calling or texting with customers served by another carrier. We are continuing to monitor the situation,” Verizon said in an emailed statement. 

The company received nearly 3,400 outage reports around 10 a.m. ET, according to Downdetector. Most users reported issues with their mobile phone. 

T-Mobile outage reports

Nearly 1,700 customers reported outages by 10 a.m. ET. Similar to Verizon, T-Mobile said they are operating normally and that customers were having trouble contacting people on other networks.