# aligned multi-line equation with intertext and block-wise numbering

I try to reproduce the output that is generated by:

\begin{aligned} (x-x_1)^2 + (y-y_1)^2 & = r_1^2 \\ (x-x_2)^2 + (y-y_2)^2 & = r_2^2 \\ (x-x_3)^2 + (y-y_3)^2 & = r_3^2 \\ \end{aligned} \label{label a}
\begin{aligned} (x-x_k)^2 + (y-y_k)^2 & = r_k^2 \end{aligned} \label{label b}


but make the two aligned blocks use the same alignment (as if it was just one align block. I tried to do this with just one align block + intertext for the line of text in the middle. But this gave me 4 lines of equation with 4 individual numbers which is not desired.

Like this?

\documentclass{article}
\usepackage{mathtools}
\begin{document}
\begin{align}
(x-x_1)^2 + (y-y_1)^2 & = r_1^2 \notag\\
(x-x_2)^2 + (y-y_2)^2 & = r_2^2     \label{label a}\\
(x-x_3)^2 + (y-y_3)^2 & = r_3^2 \notag

\shortintertext is from mathtools package and gives a tighter spacing than \intertext.