Facebook's latest feature, Safety Check, is one of the multiple reasons why it's more useful to use social media to contact loved ones during crises. See how the feature works. (Jhaan Elker/The Washington Post)

Three explosions that rocked Brussels on Tuesday left dozens dead. And in their aftermath, a strained cellphone network has left officials urging worried friends and family members to turn to social media to check on their loved ones.

Belgian Deputy Prime Minister Alexander De Croo repeatedly advised the public to use different social networks, such as Facebook, WhatsApp and Twitter — where #Brussels is trending worldwide — while connected to WiFi to communicate.

The Belgian Crisis Center also recommended that those outside Belgium try to reach people "through social media first."

But even while recommending online methods to communicate, the Crisis Center advised against streaming audio or video to avoid overloading the local Internet. The major Belgian broadband provider Telenet announced that its WiFi hotspots across the country would be free for 24 hours but warned that the influx of users might lead to congestion on its network.

Facebook also has activated the Safety Check feature for users in Brussels. The feature allows people in the area of a disaster to confirm that they are okay. The company first turned on Safety Check after the Paris attacks late last year, when about 4.1 million people used it in the first 24 hours after the coordinated assault.