Well, it is Wikipedia...
Closest I can find (there, FWIW,) is :
"... The Chinese soldiers ringing the Legation Quarter fired a few shots, wounding a Belgian woman, and then fled. It was 2:30 p.m on 14 August. "
Edit: "... Isolated legations, such as the Spanish and Belgian, and foreign businesses were abandoned.["
I found these unrelated to your questions statements interesting:
"... The relief of the siege at the Peitang did not take place until 16 August. Japanese troops stumbled across the Cathedral that morning but, without a common language, they and the besieged were both confused. Shortly, however, French troops arrived and marched into the Cathedral to the cheers of the survivors..."
I guess bilingualism was a later development...
A somewhat 'hostile' view of the location of the Cathedral today. Time always wins over man's efforts in this phase of history. The Belgian Legation is mentioned but nothing about any soldiers.
Edit: dropped link replaced.
http://www.drben.net/ChinaReport/Beijing/Landmarks-Hotspots/DongCheng/Foreign_Legation_Quarter-Former/Dongjiaomin_Xiang_Catholic_Church/Dongjiaomin_Catholic_Church.htmlThere is a picture of a 1916 map of the legations on the page.
Gracias,
Glenn