BEIRUT – Syrian troops rushed dozens of tanks and reinforcements Wednesday toward Aleppo, the country’s strategically vital commercial capital, in a bid to crush a rebel advance that has spread to wide swaths of the sprawling city.

As five days of fighting in Aleppo intensified, and with rumors swirling of a final showdown in that city, neighboring Turkey tightened its borders but said refugees will be allowed through.

“We are expecting a big attack on Aleppo,” Mohammed Saeed, an activist based in Aleppo, told The Associated Press. “People are worried they might face random shelling while fleeing.”