Complex sentence: While the roof and upper ring were felled as planned, the eastern wall and the northwest gate of the Dome were still standing after the implosion; demolition officials stated that these sections would be brought down by mechanical demolition.
Split into simpler sentences: While the roof and upper ring were felled as planned, the eastern wall and the northwest gate of the Dome were still standing after the implosion. Demolition officials stated that these sections would be brought down by mechanical demolition.